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ECCOMAS NEwSlEttEr
SEptEMbEr 2010
EuropEan Community on Computational mEthods in appliEd sCiEnCEs
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EuropEan Community on Computational mEthods in appliEd sCiEnCEs
Forward.............................................................................................3 Manolis PaPadrakakis
ECCm 2010 - paris...........................................................................4 olivier allix and Peter Wriggers
CFd 2010 - lisbon.............................................................................6 Jose C. F. Pereira
ECComas thEmatiC ConFErEnCEs in 2011............................................8
ViCE prEsidEnt oF ECComas - pEkka nEittaanmäki..................................9 tiMo tiihonen
ECComas 2010 awards..................................................................10
Grand slam ChallEnGEs in EnGinEErinG sCiEnCE with nEural ComputinG : Computational EarthquakE EnGinEErinG...............................................11 tadeusz BurCzynski and nikos d. lagaros
nurbs - EnhanCEd FinitE ElEmEnt mEthod (nEFEm)............................16 ruBén sevilla
stabilizEd FinitE ElEmEnt mEthod For hEat transFEr and turbulEnt Flows insidE industrial FurnaCEs...............................................................19 elie haCheM
ECComas 2012 ..............................................................................22
aCtiVitiEs oF thE sErbian soCiEty For Computational mEChaniCs in 2010....23 Milos koJiC
announCEmEnts...........................................................................23
ECComas wEbsitE ..........................................................................24
ContEnts
ekkehard raMM
universität stuttgart
viCe-President oF eCCoMas
Pedro díez
universitat PolitéCniCa de Catalunya
seCretary oF eCCoMas
ECComas nEwslEttEr - sEptEmbEr 2010 all rights reserved By authors.
tEChniCal Editorkati valPe
university oF Jyväskylä
EditorsManolis PaPadrakakis
national teChniCal university oF athens
President oF eCCoMas
Pekka neittaanMäki
university oF Jyväskylä
viCe-President oF eCCoMas
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The three main bodies of ECCOMAS, namely the Executive Committee, the Managing Board and the General Assembly convened in Paris in May 2010 during the ECCM Conference and elaborated on a number of issues for enhancing the activities of ECCOMAS and making it more visible in the European as well as in the international scientific community. More discussion on the future actions will be held and decisions on a number of issues are expected to be taken during the Executive Committee and Managing Meetings scheduled on November 25–26th, 2010, in Stuttgart.
Manolis PaPadrakakis
President oF eCCoMas
Since the publication of the last printed edition of the ECCOMAS Newsletter earlier this year, two major ECCOMAS events have taken place which attracted the interest of a large number of researchers from all over the world. The IV European Conference on Computational Mechanics in Solids, Structures and Coupled Problems in Engineering (ECCM 2010), 16–21 May 2010, Paris, France and the V European Conference on Computational Fluid Dynamics (CFD 2010), 14–17 June 2010, Lisbon, Portugal had an attendance of approximately 2.600 participants and set a new record of participation for these conferences. Reports on these two events are presented in the pages of this Newsletter. During these conferences, the Ludwig Prandtl and Leonhard Euler Medals were conferred to eminent researchers in the field, as well as the Olek C. Zienkiewicz and Jacques Luis Lions Awards for young investigators in Computational Engineering Sciences and Computational Mathematics, respectively. In addition to these
Medals and Awards, the two best PhD theses Awards in Computational Solid and Structural Mechanics and in Computational Fluid Dynamics for the year 2009 were also bestowed. Details on the recipients of the Medals and Awards are given in page (10).
In the year 2011 many activities and events supported by ECCOMAS will take place. It is worth noting that 22 Thematic Conferences on a large range of topics in Computational Mechanics Applied Science of Engineering are scheduled for 2011 and can be read about on page 8. This electronic issue of ECCOMAS Newsletter also contains articles on the Vice President of ECCOMAS P. Neittaanmäki, the applications of neural computing in earthquake engineering (pages 11–15), summaries of the two best PhD theses selected for the year 2009 (pages 16–18 and 19–21), announcements for future events organized by the ECCOMAS Member Associations (page 23) and the new main page of the ECCOMAS web site (page 24).
Forward
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EuropEan Community on Computational mEthods in appliEd sCiEnCEs
ECCm-2010Fourth EuropEan ConFErEnCE on Computational mEChaniCs « solids, struCturEs and CouplEd
problEms in EnGinEErinG »
The fourth E u r o p e a n Conference on Computational M e c h a n i c s took place May 16-21, 2010 at the Congress Center of Paris (Palais des Congrès) under the auspices of ECCOMAS andIACM. It was jointly orga-nized by France and Germany under the umbrella of national associations (CSMA in France and GAMM and GACM in Germany) acting in the field. The local organizing committee involved three laboratories of the south of Paris, LMT-Cachan (ENS de Cachan), LMS (Ecole Polytechnique), LMSSMAT Ecole Centrale de Paris) and CEA-Saclay where most of the work has been done by Thierry Charras (General Secretary) and by Antoine Letellier (Web site).
The success of the conference went far beyond the expectation of the organizers with 2100 abstract submissions from which about 1880 papers were selected for oral presentations. This included a participation of about
600 PhD students. In addition five plenary speakers and 36 semi-plenary speakers were elected by the ECCM-S committee of ECCOMAS and by the German-French Scientific Committee. The participants represented 61 countries, see Fig. 1, 80% of the speakers came from Europe.
This success can surely be attributed to the organizers of the 110 Mini-Symposia. The following repartition of participants by topics depicts main subjects discussed during the conference.Figure 1: the top 25 countries represented at ECCM-2010
Figure 2: view of the main auditorium during the last presentation of the conference
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• Computational strategies, solution algorithms, high-performance computation 277
• Multiple scales, homogenization, heterogeneous media 222
• Dynamics, vibrations, impacts, waves and related problems 180
• Coupled problems, multifield and multiphysics modelling 168
• Fracture, failure, fatigue, lifetime assessment 137
• Contact mechanics and related issues 123
• Biomechanics 112• Computational modelling of
materials 111• Industrial applications 108• Optimization, control, design,
sensitivity analysis 103• Identification, inverse problems 97• Mechanics at small scales,
microstructure modelling 82• Uncertainty, probabilistic and
stochastic approaches 82• Data processing, image
processing and related topics 71• Modelling of processes 48• Adaptativity, verification and
validation 47
ECCM-2010 has also hosted three events which show the participation of industry partners: the MAAXIMUS Public Forum from the European Community’s Seventh Framework
Programme FP7/2007, the E-CAero Special Session and a session organized by CLAROM (Club for research on offshore structures).
The conference provided time for scientific and social interaction either at the large dedicated space in the Palais des Congrès or during the banquet of the conference on the tour boat and in the City hall of Paris.
The two chairman of the conference hope that ECCM-2010 has met the expectation of all participants both scientifically and socially, and are deeply indebted to the community for the large attendance of all sessions during the entire week.
olivier allix and Peter Wriggers
Figure 3 : View of the banquet : a) in the « salle des fêtes » b) « salon des arcades » of the City hall c) on the Seine.
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ECComas CFd 2010lisbon, portuGal, 14–17 JunE 2010
The 5th European Conference on Computational Fluid Dynamics, CFD2010 was held on June 14–17, 2010, at National Engineering Laboratory (LNEC) in Lisbon, Portugal. This was the fifth installment in a series that started in 1994, showing a trend of growth either in paper submission or participants.
The Portuguese Association of Theoretical, Applied and Computational Mechanics (APMTAC) locally organized the CFD2010 conference, in collaboration with the Instituto Superior Técnico (IST) and LNEC.
The papers submission was more numerous than expected (945) and all abstracts were reviewed by at least two members of the Scientific Committee. A total of 551 oral communications were accepted for presentation organized into 110
thematic sessions, including 36 mini symposia and 2 special technological sessions. In addition there was 65 papers in two poster-sessions. The conference had a total of 610
participants from 48 countries of the five continents. Unavoidably, to make this happen in four days, it was necessary to work in parallel with 11 simultaneous sessions. The
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geographic distribution of the participants was as follows: Germany: 109; France: 58; North America: 47; Portugal: 42; Netherlands: 33; Spain: 33; UK: 29; Belgium: 27; East Asia: 24; Czech Rep.: 21; Italy: 21; Poland: 15; Russia: 15; Sweden: 14; Japan: 12; Norway: 10; 13 other European countries: 57; Africa: 4; South America: 15; Australia: 4; other countries: 20.
The Honorary Chairpersons were Prof. Eduardo Arantes e Oliveira, IST/Technical University of Lisbon, Portugal and Prof. Charles Hirsch, Vrije Universiteit Brussels, Belgium. The Executive Committee of CFD2010 were M. Papadrakakis (President of ECCOMAS), E. Oñate (President of IACM), Polytechnic University of Catalonia, C. A. Mota Soares (President of APMTAC), IST/Technical University of Lisbon, J. C. F. Pereira (Chairperson) IST/Technical University of Lisbon, A. Sequeira (Co-Chairperson) IST/Technical University of Lisbon, H. Deconinck (Co-Chairperson) von Karman Institute and J. Periaux (Co-Chairperson) Polytechnic University of Catalonia.
In the opening ceremony M. Papadrakakis, President of ECCOMAS, addressed the audience. He eloquently evoked the contribution of the previous Presidents and stressed the present and future role of ECCOMAS. He awarded the ECCOMAS Award for the Best PhD Thesis on Computational Methods in Applied Science and Engineering 2009 to Dr. Elie Hachem (Ecole Nationale Supérieure des Mines de Paris, France) whose thesis is entitled “Stabilized Finite Element Method for Heat Transfer and Turbulent Flows inside Industrial Furnaces”. This thesis is an outstanding work in Computational Methods combining excellent knowledge of both theory and practice.
The J. L. Lions Award for Young Scientists in Computational Mathematics Awards 2010 were handed over to the winners Jose Ramón Fernández García, Universidade de Santiago de Compostela, Spain and to Sonia Fernández-Mendez , Universitat Politècnica de Catalunya, Spain.
The conference revolved around the following themes: Computational Fluid
Dynamics, Computational Acoustics, Computational Electromagnetics, Computational Mathematics and Numerical Methods, Optimization and Control, Computational Methods in Life Sciences. Eminent researchers from Europe and USA presented nine invited lectures by T.J. Hughes, F. Bassi, P. Koumoutsakos, L. Vervisch, N. D. Sandham, J.C. Courty, L. Eça, T. Colonius, and W. A. Wall.
The proceedings have appeared in the following form:
• Proceedings of the V European Conference on Computational Fluid Dynamics ECCOMAS CFD 2010 J. C. F. Pereira, A. Sequeira and J. M. C. Pereira (Eds) Lisbon, Portugal, 14-17 June 2010, ISBN: 978-989-96778-1-4
• Book of Abstracts of the V European Conference on Computational Fluid Dynamics ECCOMAS CFD 2010 J. C. F. Pereira, A. Sequeira, J. M. C. Pereira, J. Janela and L. Borges (Eds), Lisbon, Portugal, 14-17 June 2010,Vols I and II, ISBN: 978-989-96778-0-7
Jose C. F. Pereira
instituto suPerior téCniCo
lisBon, Portugal
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ECCOMAS Thematic Conferences started in 2005 and are repeated every two years in odd years with a growing number of participants:
2005 16 Thematic Conferences 2009 24 Thematic Conferences 2011 22 Thematic Conferences
1. 18th intErnational ConFErEnCE on ComputEr mEthods in matErials sCiEnCE - komplastECh 2011 Zakopane, Poland, January 16–19 httP://WWW.koMPlasteCh.agh.edu.Pl/
2. 2nd ConFErEnCE on inVErsE problEms in mEChaniCs oF struCturEs and matErial - ipm2011 Janowice, Poland, April httP://iPM.Prz.edu.Pl/
3. CFd in optimization: mEthods and appliCations Antalya, Turkey, May 16–18
4. iii intErnational ConFErEnCE on Computational mEthods in struCtural dynamiCs and EarthquakE EnGinEErinG - Compdyn 2011 Island of Corfu, Greece, May 26–28 httP://WWW.CoMPdyn2011.org/
5. Computational modElinG oF FraCturE and FailurE matErials and struCturEs Barcelona, Spain, June 6–8 httP://Congress.CiMne.uPC.es/CFraC2011/Frontal/deFault.asP
6. Computational analysis and optimization - Cao2011 Jyväskylä, Finland, June 9–11 httP://WWW.Mit.Jyu.Fi/Cao2011
7. V intErnational ConFErEnCE on adaptiVE modElinG and simulation - admos 2011 Paris, France, June 13–15 httP://Congress.CiMne.CoM/adMos2011/Frontal/deFault.asP
ECComas thEmatiC ConFErEnCEs
20118. ii intErnational ConFErEnCE
on Computational ContaCt mEChaniCs Hannover, Germany, June 15–17
9. iV intErnational ConFErEnCE on Computational mEthods For CouplEd problEms in sCiEnCE and EnGinEErinG - CouplEd problEms 2011 Kos Island, Greece, June 20–22 httP://Congress.CiMne.CoM/CouPled2011/Frontal/deFault.asP
10. workshop on hiGhEr ordEr FinitE ElEmEnt and isoGEomEtriC mEthods - hoFEim 2011 Cracow, Poland, June 27–29 httP://hoFeiM.l5.Pk.edu.Pl/
11. ii ConFErEnCE on thE ExtEndEd FinitE ElEmEnt mEthod xFEm Cardiff, UK, June 29 – July 1
12. V ConFErEnCE on multibody dynamiCs Louvain, Belgium, July 4–7 httP://sites.uClouvain.Be/MultiBody2011/index.PhP?id=5
13. smart struCturEs and matErials - smart’11 Saarland University in Saarbrücken, Germany, July 6–8
14. xi intErnational ConFErEnCE on Computational plastiCity - Complas xi Barcelona, Spain, September 7–9 httP://Congress.CiMne.CoM/CoMPlas2011/Frontal/deFault.asP
15. dEsiGn and maintEnanCE oF airFiElds Vienna, Austria, September 12–14 httP://dMair2011.ConF.tuWien.aC.at/
16. iii intErnational ConFErEnCE on mEChaniCs rEsponsE oF CompositEs
Leibniz Universität, Hannover, Germany, September 14–16 httP://WWW.CoMPosites2011.inFo/
17. int. ConFErEnCE on EVolutionary and dEtErministiC mEthods For dEsiGn, optimization and Control with appliCations to industrial and soCiEtal problEms - EuroGEn 2011 CIRA, Italian Aerospace Research Center, Italy, September 14–16
18. iV intErnational ConFErEnCE on Computational mEthods in marinE EnGinEErinG Lisbon, Portugal, September 28–20 httP://Congress.CiMne.CoM/Marine2011/Frontal/deFault.asP
19. V intErnational ConFErEnCE on tExtilE CompositEs and inFlatablE mEmbranEs Barcelona, Spain, October 5–7 httP://Congress.CiMne.CoM/MeMBranes2011/Frontal/deFault.asP
20. Vip imaGE 2011 – iii ECComas thEmatiC ConFErEnCE on Computational Vision and mEdiCal imaGE proCEssinG Algarve, Portugal, October 12–14 httP://Paginas.Fe.uP.Pt/~viPiMage/
21. ii intErnational ConFErEnCE on partiClE basEd mEthods Barcelona, Spain, October 26–28 httP://Congress.CiMne.CoM/PartiCles2011/Frontal/deFault.asP
22. intErnational ConFErEnCE on rECEnt adVanCEs in nonlinEar modEls – struCtural ConCrEtE appliCations - Coran Coimbra, Portugal, November 24–25 httP://WWW.deC.uC.Pt/Coran2011/
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ViCE prEsidEnt oF ECComaspEkka nEittaanmäki
Professor Pekka Neittaanmäki, vice president of ECCOMAS since 2004 is turning 60 in next spring. He has made a long a broad career in applied mathematics, computational sciences and beyond. Perhaps his most characteristic feature has been the ability to recognize new possibilities and paradigm changes and to extend, rather than change, his focus of interest to exploring the new emerging fields – making new friends and initiating new collaborations on the way.
After defending his PhD for exterior problems for Helmholz equation, Pekka went to Bonn to learn about finite elements and to create contacts with the young generation of German
scientists in applied mathematics. In the beginning of 80s he started building his group around FEM and optimization in Jyväskylä. Having got a touch to technology and industrial collaboration from his detour to Lapppenranta University of Technology Pekka was one of the co-initiators and the key spokesman towards the regional stakeholders of the “applied science” initiative of the University of Jyväskylä.
In the beginning of the 90’s Pekka was already active in many high level national science policy forums, publishing regularly scientific monographs and collaborating with industry with his expanding group. Pekka was elected as a vice rector of JyU before Finland joined the EU. From that position his major tour de force was to figure out how to exploit the EU regional funds to renew the university curricula and to support regional transition towards ICT based economy.
More was still to come. After the faculty of information technology and the department of mathematical information technology Pekka’s
horizon grew broader to include also the human sciences. As co founder and first head of Agora Center Pekka has actively promoted the marriage of computational sciences with many human sciences both in the “small” like analysis of neuropsychological signals of in the large like simulation of regional or national public services.
Currently Pekka serves as the Dean of the Faculty of Information Technology at JyU. He has, as one of his interests, returned to wave propagation in irregular geometries – this time in the context of nanotechnology and continues publishing international articles and monographs.
Pekka’s friends will gather to honor his 60 year to the ECCOMAS thematic conference CAO2011 in June 9–11 in Jyväskylä. More information on can be found at the conference website at
httP://WWW.Mit.Jyu.Fi/Cao2011/
tiMo tiihonen
university oF Jyväskylä
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ECComas 2010 awardsIn addition to the various activities of ECCOMAS, three medals have been established to eminent researchers, two awards for young scientists and two awards for the best Ph.D. Theses in the field of Computational Methods in Applied Sciences and Engineering.
For the two Ph.D. Awards, every member association proposes one candidate and the ECCOMAS Awards Committee selects two awardees, one in the field of “Computational Solids and Structures” and the other in field of “Computational Fluid Dynamics”. The presentation of the awards takes place annually at an appropriate Thematic event and are accompanied with a prize of 2000 Euros.
The ECCOMAS winner of the best PhD Thesis for 2009 in the field of Computational Solids and Structures is Ruben Sevilla CaRdenaS from Universitat Politecnica de Catalunya with the Thesis entitled “NURBS - Enhanced Finite Element Method” conducted under the supervision of antonio HueRta and Sonia FeRnández-Méndez. The Award was conferred at the ECCOMAS-ECCM conference in Paris on May 2010. The ECCOMAS winner of the best PhD Thesis for 2009 in the field of Computational Fluid Dynamics is elie HaCHeM from Ecole Nationale Supérieure des Mines de Paris, with the thesis entitled “Stabilized Finite Element Method for Heat Transfer and Turbulent Flows inside Industrial Furnaces” conducted under the supervision of tHieRRy Coupez and eliSabetH MaSSoni. The Award was conferred at ECOMAS-CFD conference in Lisbon on July 2010.
The two ECCOMAS Awards for young scientists are the olek CeCil zienkiewiCz Award in the field of Computational Engineering Sciences and the JaCqueS louiS lionS Award in the field of Computaional Mathematics. The awards are given every two years at the ECCOMAS Congress or at the ECCOMAS-
ECCM and ECCOMAS-CFD Conferences, respectively. It includes a Diploma, free registration to the respective Conference and a prize of 2000 Euros.
The ECCOMAS winner of the olek CeCil zienkiewiCz Award for young scientists in Computational Engineering Sciences is MaRino aRRoyo from Universitat Politecnica de Catalunya, Spain for his work on the mechanical simulation of carbon nanotubes and the meshfree methods.
The ECCOMAS winner of the JaCqueS louiS lionS Award for young scientists in Computational Mathematics is awarded ex aequo to Sonia FeRnadez-Mendez from Universitat Politecnica de Catalunya, and to JoSe RaMon FeRnandez GaRCia from University of Sandiago de Compostella, Spain.
The ECCOMAS leonHaRd euleR Medal for outstanding and sustained contribution to the area of computational solids and structural mechanics and coupled problems in engineering and the ludwiG pRandtl Medal for outstanding and sustained contribution to the area of computational fluid dynamics, are conferred every two years at the ECCOMAS main Conferences. The winner of the ludwiG pRandtl Medal is RoGeR oHayon from the Structural Mechanics and Coupled Systems Laboratory Conservatoire National des Arts et Metiers (CNAM), Paris, France. Professor Roger Ohayon has made outstanding contributions in the fields of computational fluid dynamics, fluid-structure interactions, structural damping, and smart structures. His
research in computational models for fluid-structure interactions has provided the engineering society effective tools towards better design of structures containing liquids and gas. In addition, he is one of the pioneers in smart and intelligent structure research for vibration reduction treatments applying hybrid passive/active control methodologies.
The winner of the leonHaRd euleR Medal is beRnHaRd SCHReFleR from Structural Mechanics, Dipartimento di Costruzioni e Trasporti, Università degli Studi di Padova, Italia. Professor Bernhard Schrefler is a worldwide leading figure in computational sciences, in particular in the theory and numerical treatment of multi-physics problems and their application in the area of civil and environmental engineering with a special interest in structural and material mechanics. Typical examples are coupled formulations for geotechnical problems, soil sciences, and simulation of tunnels under fire and thermo-electro-mechanical models for the construction of fusion reactors with special emphasis on multi-scale modeling.
ECCOMAS has also established the Ritz-GaleRkin Medal which is the highest award given by ECCOMAS. It honours individuals who have made outstanding, sustained contributions in the field of computational methods in applied sciences. The medal carries the images of Ritz and GaleRkin in recognition of the synergy between mathematics, numerical analysis, mechanics of solids and structures, fluid dynamics, and other engineering disciplines. The medal is conferred every four years at the ECCOMAS Congress
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Grand slam ChallEnGEs in EnGinEErinG sCiEnCE with nEural ComputinG:
Computational EarthquakE EnGinEErinG
Neural networks are in the dock not only because they have been hyped to high heaven, (what hasn’t?) but also because you could create a successful net without understanding how it worked: the bunch of numbers that captures its behavior would in all probability be “an opaque, unreadable table... valueless as a scientific resource”.
Roger Bridgman, 1996
Earthquake Engineering is a relatively new multi-disciplinary and constantly evolving scientific topic with great economic and social importance encompassing structural analysis and design, computational methods and material science, both in a deterministic and stochastic context. Recent seismic events in developing countries (Figure 1), as well as in modern cities of developed countries, have shown the large life and economic losses that can occur after a strong earthquake as a consequence of bad design and construction. High quality training and education of professionals and researchers in the field of analysis and design of earthquake resistant structures is of paramount importance in reducing the seismic risk in earthquake vulnerable regions. During the last century, significant advances have been taken place towards the improvement of the seismic design codes. The philosophy underlying modern codes is that the building structures should remain elastic for frequent earthquake events.
Under rare earthquakes, however, damages are allowed given that life safety is guaranteed. Hence, the main task of the design procedures is to achieve more predictable and reliable levels of safety and operability against natural hazards. Through extensive research studies it was found that the Performance-Based Design (PBD) [1] concept can be integrated into a structural design procedure in order to obtain designs that fulfil the provisions of a safety structure in a more predictable way.
According to the PBD framework the structural behaviour is assessed in multiple hazard levels of increased intensity. Consequently, it is very important to use robust and computationally efficient methods for predicting the seismic response of the structure required to assess its capacity under different seismic hazard levels with reduced computational effort. Traditionally, structural analysis methods were based on rigorous scientific procedures that are formed on mathematical methods and the principles of theoretical mechanics
and led to the implementation of numerical simulation methods based on discretized continua. Since early 80’s new families of computational methods, termed as Soft Computing (SC) methods, have been proposed. SC methods are based on heuristic approaches rather than on rigorous mathematics. Despite the fact that these methods were initially received with suspicion, they have turned out in many cases to be surprisingly powerful, while their use in various areas of engineering science is continuously growing. Neural Networks, Evolutionary Algorithms, Artificial Immune Systems and Fuzzy Logic are among others some of the most popular categories of SC methods.
Neural networks feature adaptive learning, self-organizing capability during training and fault imprecision during applications. The main advantage of using neural networks is that they can deal with problems that do not have an algorithmic solution or for which an algorithmic solution is too complex to be found. Neural Computing (NC) have so far been applied in many engineering fields, on the other hand computational earthquake engineering is a computationally intensive field where NC have been used for the simulation of the structural behaviour under static or dynamic loading. Performance-Based Design (PBD) is the current trend for the seismic design of structural systems where the structural performance is assessed for multiple hazard levels. PBD framework
Figure 1. Global seismicity-earthquakes occur everywhere
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is performed by means of either nonlinear static or nonlinear dynamic analysis (NDA); in the later case multiple NDA have to be performed for every hazard level requiring significant computational effort. The predicted structural response by ANN can be used in the PBD framework when dynamic analyses are performed, aiming at reducing the excessive computational cost.
pErFormanCE basEd dEsiGn
The requirements and provisions of seismic design codes have been based on experience and observations and they were periodically revised after disastrous earthquakes. Seismic design codes usually rely on a single design earthquake for assessing the structural performance against earthquake hazards. As a consequence, these codes have many inherent assumptions built in the design procedure regarding the seismic behaviour of structures and the characteristics of earthquake loading. Severe damages caused by recent earthquakes triggered a number of questions by the engineering community regarding the reliability of the current seismic design codes. Given that the primary goal of contemporary seismic design is the protection of human life in connection to an economic design, it is evident that additional performance targets and earthquake intensities should be considered in order to assess the structural performance for many hazard levels. In the last decade the concept of performance-based structural design under seismic loading conditions was introduced. In PBD, more accurate analysis procedures are implemented based on the nonlinear structural response.
Most of the current seismic design codes belong to the category of prescriptive or limit state design procedures where if a number of conditions, expressed
primarily in terms of forces and secondarily in terms of displacements are satisfied, the structure is considered safe and no collapse is assumed to occur. A typical limit state based design can be viewed as one (i.e. ultimate strength) or two (i.e. serviceability and ultimate strength) limit states approach. All contemporary seismic design procedures are based on the concept that a structure will avoid collapse if it is designed to absorb and dissipate the induced kinetic energy during the seismic excitation [2]. According to a prescriptive design code the strength of the structure is evaluated at one limit state, between life-safety and near collapse, using a response spectrum-based loading corresponding to one earthquake hazard level. In addition, the serviceability limit state is usually checked in order to ensure that the structure will not deflect or vibrate excessively. On the other hand, PBD is a different approach which includes, apart from the site selection and the consideration of the design stages, the performance of the structure after construction in order to ensure reliable and predictable seismic performance over its life.
The main task in a performance-based seismic design procedure is the definition of the performance objectives. A performance objective is defined as a given degree of system performance response for a specific hazard level. The definition of the earthquake hazard, according to FEMA-350, includes parameters such as direct ground fault rupture, ground shaking, liquefaction, lateral spreading and land sliding. Ground shaking is the only earthquake hazard that structural design codes directly address. Ground shaking hazard is defined by means of a hazard curve, which indicates the probability that a measure of seismic intensity (e.g peak ground acceleration or 1st mode spectral acceleration) will be exceeded over a certain period of time. The combination of one performance level with an earthquake hazard level results to a performance objective.
Computational EFFort
Seismic analysis and design of structures is an extremely computational intensive task since the prediction of the nonlinear dynamic response is required, in order to assess the structural performance for different hazard levels, which is in addition influenced by a number of inherently uncertain parameters. Such parameters are, among others, the material properties, the workmanship, the hysteretic behaviour of structural members and joints, the support conditions. The intensity and the earthquake ground motion characteristics are also random. Furthermore, uncertainty is also involved in the design procedure that would be adopted as well as in the numerical simulation of the structure. In order to account for as many as possible of the above uncertainties a reliability-based, in conjunction with a performance-oriented, approach should be considered. If, in addition to system uncertainties, structural optimization is also implemented, by substituting the traditional “trial and error” procedure with an automated optimization design procedure for obtaining not only a feasible but also the best possible design, then the computational cost increases dramatically.
Figure 2 [3] depicts a qualitative assessment of the computational effort required for solving different types of problems starting from the dynamic analysis with nonlinear system response to the most demanding and complicated one, but very essential for a safe and economic design, reliability combined with robust earthquake design optimization with nonlinear system response. The computational effort becomes excessive, increased by orders of magnitude, with regard to the required effort for the corresponding deterministic problems. In these cases, the need for reducing the computing times becomes much more pronounced. The only way to attempt
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the solution of these problems is to achieve six to seven orders of magnitude reduction in the required computational effort. The reduction of the computational cost can be achieved with a synergy of the following actions during the design procedure: (i) Applying reliable and efficient optimization algorithms for improving the design procedure. (ii) Adequately treating the system uncertainties including a proper selection of the seismic loading. (iii) Implementing artificial intelligent methodologies that combine accuracy and robustness.
nEuroComputinG sChEmEs
Nonlinear dynamic analysis is an important procedure for estimating the structural response that is required for the design of earthquake resistant structures. The main scope of an adaptive NC scheme is to predict with acceptable accuracy the seismic response of real-world structural systems for multiple hazard levels in an affordable computational time. For this purpose neural networks are incorporated into a performance based design methodology aiming at reducing the computational cost of nonlinear dynamic analysis. The structural performance is usually examined in three hazard levels of increased intensity, namely 50%, 10% and 2% probability of exceedance in 50 years.
A number of uncorrelated artificial accelerograms for each hazard level, produced from the smooth elastic design spectra (Figure 3), can be used.
Two schemes are examined: (i) A non-adaptive scheme, where a neural network is trained once over a number of accelerograms and it is then used for predicting the structural seismic response for all time steps of the time history and (ii) An adaptive scheme, where a neural network is also trained once over a number of accelerograms but in specific predefined time steps the predictions of NN are corrected. For both schemes examined the artificial neural networks implemented are designated as follows:
where i, j denote the number of previous time steps and the number
of the artificial accelerograms that are used for the ANN training and k denotes the scheme used. The two prediction schemes are shown in Figure 4.
non-adaptiVE sChEmE
The objective is to train NN that will be able to predict the time history of the displacement of the diaphragm centre along the longitudinal (X) and transverse (Y) directions. When non-linear behaviour is considered the response is highly nonlinear as it can be seen by the stress-strain hysteretic curve of Figure 5 corresponding to the column C1 of the ground storey (see Figure 6). The performance of the non-adaptive scheme is shown in Figure 7(a), where a deviation of the predicted response versus that obtained by with a full finite element analysis is observed in the last time steps. This is due to the fact that, the prediction phase is performed having
( )njNN k
Glossary oF aCronyms:
Case 1 Dynamic AnalysisCase 2 Dynamic Design OptimizationCase 3 Dynamic Multi-objective Design OptimizationCase 4 Reliability Dynamic AnalysisCase 5 Reliability-Based Dynamic Design OptimizationCase 6 Reliability-Based Earthquake Design OptimizationCase 7 Robust Dynamic Design OptimizationCase 8 Robust Earthquake Design OptimizationCase 9 Reliability-Robust Dynamic Design OptimizationCase 10 Reliability-Robust Earthquake Design Optimization
Figure 2. Computational effort [3]
Figure 3. (a) 5%-damped elastic design spectra and (b) three typical artificial accelerograms for the three
hazard levels
Figure 4. Description of the (a) non adaptive and (b) adaptive neurocomputing schemes
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a recurrent connection between the inputs and the outputs the error is accumulated in the last time steps.
adaptiVE sChEmE
The adaptive scheme is based on the principles of static condensation. The basic static condensation procedure can be illustrated by the use of matrix notation. The equilibrium equations can be written in matrix form as follows:
where uE indicates the degrees of freedom to be eliminated and uC the condensed degrees of freedom which are associated with the reduced stiffness matrix. The solution of the second submatrix equation for uE, yields:
Knowing the response of the structural system along the condensed degrees of freedom, the corresponding response along the eliminated ones is obtained by the previous Equation. The basic idea of the adaptive scheme in the framework is to perform conventional nonlinear dynamic analyses in predefined time intervals in order to correct the predictions of the ANN. The initiation of the conventional nonlinear dynamic analysis procedure requires the displacements and accelerations
at the predefined restart time step tre for every degree of freedom of the structural system. However, this information is not
performance of the adaptive scheme is shown in Figure 7(b).
numEriCal rEsults
Due to space limitations the numerical results will be restricted to the computational efficiency achieved by the implementation of soft computing methodologies, such as NN predictions of the structural response, for addressing optimum design problems. The interested reader is refereed to Refs. [4-9] for implementing advanced optimization algorithms incorporating multi-database cascade evolutionary algorithms and the neurocomputing schemes. The 3D RC building
having a non symmetrical plan view, shown in Figure 9, is considered for implementing the NC scheme in PBD optimization while Figure 10 depicts the prediction capabilities of NC scheme. The computational effort required for performing the performance based design optimization is presented
Figure 5. Two storey 3D RC building: Stress-strain hysteretic curve
Figure 6. Two storey 3D RC building: (a) Plan and (b) side views
Figure 7. Two storey 3D RC building: Performance of the (a) non-adaptive and (b) adaptive scheme
Figure 8. Model reduction
available by the neural network-based surrogate model which provides the time history of the two translations UX,i(t), UY,i(t) and the rotation ΘZ,i(t) of the ith diaphragm, as shown in Figure 8. The
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in Table 1. In particular the computational cost of Cases 7 and 10 is presented. It has to be noted that the cost for the conventional implementations is an estimation due to the excessive computing time required by these two design cases. As can be seen, more than four orders of magnitude saving in computational cost is achieved with the NC scheme implemented in parallel computing environment compared to the conventional structural analysis.
rEFErEnCEs
[1] FEMA-350: Recommended Seismic Design Criteria for New Steel Moment-Frame Buildings. Federal Emergency Management Agency, Washington DC, 2000.
[2] Mitropoulou ChCh, Lagaros ND, Papadrakakis M. Economic building design based on energy dissipation: a critical assessment,
Bulletin of Earthquake Engineering; DOI: 10.1007/s10518-010-9182-x, 2010.
[3] Papadrakakis M. Seismic Design of Structures: a Challenge for Computational Mechanics, IACM Expressions; 22(22-27), 2008.
[4] Charmpis DC, Lagaros ND, Papadrakakis M. Multi-database
exploration of large design spaces in the framework of cascade evolutionary structural sizing optimization, Computer Methods in Applied Mechanics and Engineering; 194(30-33), 3315-3330, 2005.
[5] Papadrakakis M, Lagaros ND. Reliability-based structural optimization using neural networks and Monte Carlo simulation, Computer Methods in Applied Mechanics and Engineering; 191(32), 3491-3507, 2002.
[6] Burczynski T, Poteralski A, Szczepanik M. Topological evolutionary computing in the optimal design of 2D and 3D structures. Engineering Optimization; 39(7):811-30, 2007.
[7] Białecki RA, Burczyński T, Długosz A, Kuś W, Ostrowski Z. Evolutionary shape optimization of thermoelastic bodies exchanging heat by convection and radiation. Computer Methods in Applied Mechanics and Engineering; 194(17):1839-1859, 2005.
[8] Burczyński T. Evolutionary and immune computations in optimal design and inverse problems. Chapter 2in: Advances of Soft Computing in Engineering (Ed. Z.Waszczyszyn), Springer 2010, 57-132.
[9] Jarosz P., Burczyński T. Coupling of immune algorithms and game theory in multiobjective optimization. In: Artificial Intelligence and Soft Computing (Eds. L.Rutkowski et al), Springer 2010, 500-5007.
tadeusz BurCzyński
silesian university oF teChnology
Poland
nikos d. lagaros
national teChniCal university oF athens
greeCe
Figure 9. Six storey 3D RC building: Plan view
Figure 10. Six storey 3D RC building: Roof floor displacement time history for the 2/50 hazard level (NN10
5 adapt5)
Formulation Monte Carlo Simulations
Computing Time (days)
Conventional* NN
Case 7 - 1.02E+02 6.86E-04
Case 10 (2%) 10,000 2.19E+04 7.93E+00
Case 10 (0.1%) 100,000 1.23E+05 7.13E+01
*Estimated
Table 1. Six storey 3D RC building: Performance of the methods
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nurbs-EnhanCEd FinitE ElEmEnt mEthod (nEFEm)
introduCtion
Non-uniform rational B-splines (NURBS) are nowadays widely used for geometric description in computer aided design (CAD). This fact has motivated the development of novel finite element (FE) techniques considering exact CAD descriptions of the computational domain [1,2].
NURBS-Enhanced Finite Element Method (NEFEM) is a powerful methodology that allows incorporating the usual NURBS boundary representation of the domain into an existing FE code. For elements not intersecting the boundary a standard FE rationale is used, and only for curved elements a specific definition of the curved entities is introduced using the NURBS boundary representation. For those elements, a specifically designed polynomial interpolation and numerical integration are proposed. The approximation is defined in Cartesian coordinates, ensuring reproducibility of polynomials in the physical space, and for the numerical integration, efficient strategies are proposed. The methodology proposed here has the great advantage of working with the usual NURBS boundary representation of the domain, and the treatment of trimmed and singular NURBS is straightforward, providing a seamless bridge between CAD and finite element analysis (FEA).
nEFEm ConCEpt
Given a domain whose boundary is given by NURBS surfaces, a regular partition in tetrahedrons is assumed, see for instance Fig. 1.
As usual in FE mesh generation codes, it is assumed that every curved boundary face belongs to a unique NURBS. Note however that the piecewise definition of each NURBS is independent on the mesh discretization. Thus, NURBS parameterization can change its definition within one face (Fig. 2).
An element without any edge or face in contact with NURBS boundaries has planar faces and it is defined and treated as a standard FE. Therefore, in the vast majority of the domain, interpolation and numerical integration are standard, preserving the computational efficiency of classical FEM. Specifically designed numerical strategies for interpolation and integration are needed only for those elements affected by NURBS boundaries.
dEFinition oF CurVEd ElEmEnts
Curved elements are defined in terms of the NURBS boundary representation of the domain.
As an example, let us consider an element with a face on the NURBS boundary, see Fig. 3. The face on the NURBS boundary is defined by the image of a straight-sided triangle in the parametric space of the NURBS. Interior curved faces are defined as a convex linear combination of the curved edge and the interior node. Note that this approach to define interior curved faces ensures the same definition of an interior curved face as seen from the two elements sharing this face. With this definition of curved faces, a curved tetrahedral element with a face on the NURBS boundary corresponds to a convex linear combination of the curved NURBS face and the interior vertex.
It is worth remarking that a standard linear mesh generator only provides the vertices and straight edges in the physical domain. In order to incorporate the NURBS boundary description, straight edges are replaced by edges over the true NURBS surface.
Fig. 1: Cut through an unstructured tetrahedral NEFEM mesh
Fig. 2: Knot lines of the NURBS surfaces in blue and surface triangulation
Fig. 3: Curved tetrahedral element with a face on the NURBS boundary, showing a face on the NURBS
boundary in green and a face with an edge on the NURBS boundary in blue
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workinG with CurVEd ElEmEnts
NEFEM considers nodal polynomial interpolation in each element. To ensure reproducibility of polynomials in the physical space, NEFEM defines the approximation for curved elements directly with Cartesian coordinates. Recall that in isoparametric FEM, the approximation is defined in a reference element. However, contrary to NEFEM, the definition of the polynomial basis for high-order curved elements does not ensure reproducibility of polynomials in the physical space.
Efficient numerical integration is a key issue in NEFEM. All integrals in elements not having an edge or face in contact with the NURBS boundary are computed using standard procedures. For an element affected by the NURBS boundary representation, it is necessary to design specific quadratures. As an example, let us consider an element with a face on the NURBS boundary. The element is parametrized using the mapping represented in Fig. 4. This mapping decouples the complexity of the NURBS with respect to the third direction. Therefore, efficient integration is performed using a tensor product of a triangle quadrature and a one dimensional quadrature. This parametrization is in fact linear with respect to the third direction, allowing exact integration in this direction. In addition, this strategy allows a seamless treatment of trimmed and singular NURBS surfaces, only by modifying the quadrature on the NURBS parametric space.
numEriCal ExamplEs and Comparison
Several numerical examples are used to demonstrate the applicability and benefits of the proposed methodology. First example considers the numerical solution of a second-order elliptic problem using a continuous Galerkin formulation. Using an ultra-coarse mesh of a sphere with only eight curved elements, geometric error introduced by isoparametric or Cartesian FEs is clearly observable, whereas the exact boundary representation is always used with NEFEM. Fig. 5 shows the numerical solution over the surface of the sphere using isoparametric FEs and NEFEM.
In this example, geometry error induces sizable errors in the numerical solution. In fact, the maximum error in the solution for isoparametric and Cartesian FEs is controlled by the geometry error (i.e., maximum difference between the true boundary and the approximated boundary), whereas the p-convergence using NEFEM is much faster due to the exact boundary representation, see Fig. 6.
Next example considers the inviscid flow around a circle at free-stream Mach number 0.3. As pointed out in [3], discontinuous Galerkin (DG) discretization of the solid wall boundary condition is very sensitive to the geometrical description of curved boundaries. With standard linear FEs, even if the mesh is highly refined near the circle, a non-physical entropy production is observed behind the wall, see left plot in Fig. 7. With NEFEM the exact boundary representation allows convergence to the correct physical solution even with a piecewise linear approximation of the solution, see right plot in Fig. 7.
The exact boundary representation of the domain also allows computing accurate solution with ultra-coarse meshes. For instance, Fig. 8 shows the numerical solution of the inviscid flow around a RAE2822 airfoil. The computational mesh has only two elements to describe the geometry of the leading edge, and a polynomial approximation of degree eight is used to capture the flow features.
Fig. 4: Parametrization of a curved tetrahedral element with a face on the NURBS boundary used to perform
the numerical integration
Fig. 5: FEM (left) and NEFEM (right) solution of a second-order elliptic problem with
quadratic approximation
Fig. 6: p-convergence comparison for the second-order elliptic problem
Fig. 7: FEM (left) and NEFEM (right) Mach number distribution for the inviscid flow around a
circle using linear approximation
Fig. 8: Coarse NEFEM mesh and) Mach number distribution for the inviscid flow around a
RAE2822 airfoil
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Next examples show advantages of NEFEM for the numerical solution of electromagnetic scattering problems using a DG formulation.
Even for simple geometries like a circle, NEFEM shows an important improvement, not only with respect to isoparametric or Cartesian FEs (with an approximated boundary representation) but also with respect to p-FEM (with an exact boundary representation), showing that the combination of the NURBS boundary representation and Cartesian approximation proposed in NEFEM provides the most accurate results for a given spatial discretization. Fig. 9 shows the evolution of the error in the Radar Cross Section (RCS) as the degree of the approximation is increased.
NEFEM has been applied to a wide range of scattering problems showing the ability to compute accurate solutions with coarse meshes and high-order approximations, see for instance the scattered field distribution over the NASA almond in Fig. 10.
But the possibilities of NEFEM still go beyond. In the context of FEs, the size of the model is sometimes subsidiary of the geometrical complexity and not only on solution itself. In particular, FE simulation of the scattering by complex objects with small geometric details requires drastic h-refinement to capture the geometry. Moreover, for scattering applications, small geometric details are influential in the solution, especially for high frequency problems, and a simplification of the geometry may lead to important discrepancies in the computed scattered field. Nevertheless, in the NEFEM context, when small is influential it does not imply small elements.
The scattering by a complex aircraft profile is considered first, see the scattered field distribution in Fig. 11. At the front part of airfoil the profile has a small geometric feature that requires h-refinement with standard FEs, see left plot in Fig. 12. Nevertheless with NEFEM, the exact boundary representation is considered with no dependence on the spatial discretization. It is therefore possible to consider elements with a corner inside one NURBS face, see right plot in Fig. 12.
This powerful ability is illustrated in three dimensions with the simulation of the scattering by a thin plate. Using FEs, even if the desired mesh size is very large in comparison with the thickness of the plate, the minimum mesh size is given by the thickness of the plate. With NEFEM, the plate can be described using two NURBS surfaces in such a way that the minimum mesh size is not
controlled by the plate thickness, see Fig. 13, and a detailed view of a NEFEM element in Fig. 14. These elements allow computing accurate RCS patterns (Fig. 15) and, obviously, they provide a powerful strategy when explicit time marching algorithms are used because the minimum time step is not dictated by geometric features.
rEFErEnCEs
[1] R. Sevilla, S. Fernández-Méndez and A. Huerta, “NURBS-Enhanced Finite Element Method (NEFEM)”, Internat. J. Numer. Methods Engrg. 76, 56-83, 2008.
[2] T. J. R. Hughes, J. A. Cottrell, and Y. Bazilevs, “Isogeometric analysis: CAD, finite elements, NURBS, exact geometry and mesh refinement” Comput. Methods Appl. Mech. Engrg., 194, 4135-4195, 2005.
[3] F. Bassi and S. Rebay, “High-order accurate discontinuous finite element solution of the 2D Euler equations” J. Comput. Phys., 138, 251–285, 1997.
ruBén sevilla, sWansea university
Fig. 9: p-convergence comparison showing the RCS error as the degree of a
approximation is increased
Fig. 10: Coarse mesh (top) and scattered field distribution (bottom) over the surface of the almond using NEFEM and a degree of
approximation five
Fig. 11: Scattering by an aircraft profile
Fig. 12: Detail of a standard FE mesh (left) and a NEFEM mesh (right)
Fig. 13: NURBS surfaces describing a plate
Fig. 14: Detailed view of a NEFEM element
Fig. 15: RCS comparison
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stabilizEd FinitE ElEmEnt mEthod
For hEat transFEr and turbulEnt Flows insidE industrial FurnaCEs
Figure 1. Continuous heating inside a furnace
A heat treatment furnace is a complex manufacturing process to control the mechanical and physical properties of metallic components. It involves furnace control, turbulent flows, conduction within the load, convection and thermal radiation simultaneously (Fig. 1). The thermal history of each
part and the temperature distribution in the whole load are critical for the final microstructure and the mechanical properties of workpieces. It can directly determine the final quality of parts in terms of hardness, toughness and resistance. To achieve higher treatment efficiency, the major influencing factors such as the design of the furnace, the location of the workpieces, thermal schedule and position of the burners should be understood thoroughly.
Therefore, the main objective is to develop a computational methodology able to predict the furnace atmosphere
as well as the transient heat transfer to the load in a continuous heat treatment process.
Due to the complexities of the physics that may occur for such applications, most of the time, the general idea was to solve only for heat conduction
within the load and employ different assumption and simplification about the surrounding gas temperature. Different heat transfer coefficients are derived from known furnaces or previous experimental works. They are used as boundary conditions to ensure both the convective and radiation effects on and from the treated solid. However, in recent years, different environmental constrained pushed the industries to change their previous regulations. Consequently, many experimental tests must be made to recompute these coefficients. But, when dealing with a large diversity of shapes, positions, dimensions and
physical properties of these metals to heat, such operations can become rapidly very costly and time consuming.
The challenge of this work is then the development of efficient methods able to simulate complex flow problems inside industrial furnaces including
fluid-solid interaction phenomena. The tools used in this thesis are the Finite Element Method (FEM) and Computational Fluid Dynamics (CFD).
First, a multi-domain approach to solve the conjugate heat transfer for which the three modes, convective, conductive and radiative heat transfer interfere simultaneously and in both the fluid part and the solid part was introduced. The proposed numerical technique referred as the immersed volume method (IVM), allows a simple and accurate resolution, in particularly at the interface between the fluid and solid.
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It is based on the use of an adaptive anisotropic local grid refinement by means of the levelset function [1] to well capture the sharp discontinuities of the fluid-solid interface, e.g. physical properties. A fast mesh generation algorithm is used to allow the creation of meshes with extremely anisotropic elements stretched along the interface. This turned out to be an important requirement for conjugate heat transfer and multi-component devices with surface conductive layers. The strategy was to only add nodes locally at the interface, whereas the rest of domain keeps the same background size. Note also, when using an anisotropic mesh, with elements stretched in a ‘right’ direction, one could allow not only to save a lot of elements but also to well describe any complex geometry in
terms of curvature, angles,…. (Fig. 2).From computation point of view, a single grid is used for both air and solid for which only one set of equations need to be solved. Consequently, different subdomains are treated as a single fluid with variable material properties. The important aspect of the chosen strategy is that by solving the whole domain in a fully monolithic way there is no need of empirical data so as to determine the heat transfer coefficient between the treated solid
and the surrounding fluid. The heat exchange at the interface is replaced naturally by solving the convective fluid in the whole domain.
To complete, the three-dimensional finite-element (FEM) methods needed for solving the transient heat transfer and turbulent flows inside the furnaces must be capable of taking into account also the proposed fluid-solid coupling. An intensive work on various stabilized finite element methods required for computing the conjugate heat transfer and the flows are studied, implemented and analyzed.
The time-dependent convection-diffusion-reaction problem has been revisited. The Streamline Upwind Petrov-Galerkin (SUPG) and the Shock Capturing Petrov-Galerkin
(SCPG) methods were introduced and implemented. In the case of transient diffusion problems at the ingots’ level, a space-time stabilized finite element method referred as ‘Enriched-Method with time interpolation’ has been presented and analysed to treat thermal shock in numerical heat transfer.
A stabilized finite element method for the transient incompressible Navier-Stokes equations based on
the variational multiscale (VMS) principle, e.g. the decomposition of the unknowns into large scale and fine scale is presented [2]. The motivation of using these advanced methods comes from the desire of handling flows at high Reynolds number: highly convection-dominated flows which occur mainly in the furnace chamber [3].
Additionally, different turbulence models are worked out in order to justify the choice of the particular method that must be used to simulate a real industrial furnace. Two classical turbulence models were introduced, analyzed and studied: the k-epsilon model and the Large Eddy Simulation (LES) model. The main objective remained on understanding and implementing these models to open
the choice to the user to decide which methods one must use regarding the application in hand. We explicated briefly that each method offers the accuracy of the results in respect to the computational costs and the required computing time.
Thermal radiation exchange plays an important role on the overall efficiency, the quality of the heated ingots and the production rates since it is the dominant mode of heat transfer in most
Figure 2. Mesh adaptation in the vicinity of the fluid-solid interface: from the initial mesh to the final mesh
before
after
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furnaces. A study was dedicated to search and review different models for solving the radiative heat transfer. The objective was to find the best fitted model with a certain capability to take into account fluid-solid interactions phenomena (gas-walls-heated ingots). Two thermal radiation models (the P1 and Roseland models) were implemented and adapted to our multi-components problem.
All these finite element solvers are implemented using the C++ parallel finite element library, CimLib developed at the CEMEF. They represent the features dedicated to numerical abilities of the proposed approach to simulate 3D industrial furnaces with different complex charges inside (Fig. 3). The performance and the efficiency of the overall models have been demonstrated using several benchmarks and industrial applications. It is shown to be an attractive way for solving turbulent flows and heat transfer in a variety of furnaces with different boundary conditions.
rEFErEnCEs
[1] C. Gruau and T. Coupez, 3D Tetrahedral, Unstructured and Anisotropic Mesh Generation with Adaptation to Natural and Multidomain Metric, Computer Methods in Applied Mechanics and Engineering, 194 (2005) 4951-4976.
[2] A. Masud, R.A. Khurram, A multiscale finite element method for the incompressible Navier–Stokes equations, Computer Methods in Applied Mechanics and Engineering, 195 (2006) 1750–1777.
[3] E. Hachem, B. Rivaux, T. Kloczko, H. Digonnet, T. Coupez, Stabilized finite element method for incompressible flows with
high Reynolds number, Journal of Computational Physics, (2010); ISSN 0021-9991, DOI: 10.1016/j.jcp.2010.07.030.
elie haCheM eCole nationale suPérieure des Mines de Paris
Figure 3a. Streamlines and isotherms inside a 6m diameter furnace with 10 different burners and three immersed solid objects
Figure 3b. The evolution of isotherms and streamlines at different time step inside 1m3 industrial furnace with a support grid and resistant walls
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ECComas 2012EuropEan ConGrEss on Computational
mEthods in appliEd sCiEnCEs and EnGinEErinG
ViEnna, austria | sEptEmbEr 10–14, 2012
We are pleased to announce the organization of the 6th EuropEan ConGrEss on Computational mEthods in appliEd sCiEnCEs and EnGinEErinG to be held at University of Vienna. The Opening Ceremony and the First Plenary Lecture will take place in the Main Concert Hall of the Musikverein where the famous New Year’s Concert by the Vienna Philharmonic Orchestra is broadcast worldwide every year.
honorary Chairman
Herbert A. MANGChairmEn
Josef EBERHARDSTEINERHelmut J. BÖHMFranz G. RAMMERSTORFER
orGanizinG institution
Vienna University of TechnologyInstitute for Mechanics of Materials & Structures and Institute of Lightweight Design & Structural Biomechanics
ExECutiVE CommittEE Ferdinando AURICCHIOMichel BERCOVIERMichel BERNARDOUNenad BICANICTadeusz BURCZYNSKIPedro DÍEZMichael GILCHRISTCharles HIRSCHJoze KORELCTrond KVAMSDALPierre LADEVÈZEAlexander MASLOVMaria MORANDI CECCHICarlos MOTA SOARESPekka NEITTAANMAKIManolis PAPADRAKAKISCarlos PARÉSEkkehard RAMMPaul STEINMANNIsmail TUNCERDick VAN CAMPENDirk VANDEPITTE
In addition, a sCiEntiFiC CommittEE and an industrial CommittEE were formed (please see the members at the congress website).
sCiEntiFiC outlinE
ECCOMAS 2012 aims at providing a forum for presentation of both the state-of-the-art and future research directions in all fields covered by ECCOMAS.
Major fields of interest are the application of mathematical and computational methods and of modelling to areas such as fluid dynamics, structural mechanics, semiconductor modelling, electro-magnetics, chemistry, acous-tics, and multi-physics problems.
Multidisciplinary applications of these fields to critical societal and technological problems encountered in sectors like aerospace, automotive and marine industry, electronics, energy, finance, chemistry, medicine, biosciences, and environmental sciences are of particular interest.
ECCOMAS 2012 aims at fostering interdisciplinary collaboration of and interaction between researchers within and beyond the major fields of interest of ECCOMAS.
Call For mini-symposia
Distinguished colleagues are invited to organize minisymposia on particular subjects of interest. Starting in fall 2010, proposals can be submitted online through the congress website. Deadline for proposals is September 15, 2011. The prospective organizers will be informed by October 31, 2011 about the acceptance of their proposal.
Call For papErs
Authors are kindly invited to electronically submit an abstract related to the congress topics through the congress website by December 15, 2011. Instructions for preparing full length papers will be provided together with notification of acceptance of the contribution.
Updated information on ECCOMAS 2012 can be found at the congress website athttp://ECComas2012.ConF.tuwiEn.aC.at
The organizers are looking forward to welcome you in Vienna, in September 2012!
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aCtiVitiEs oF thE sErbian soCiEty For
Computational mEChaniCs in
2010
The main activities of the Serbian Society for Computational Mechanics (SSCM) are recently focused on the Journal of the Serbian Society for Computational Mechanics (JSSCM) and on the Research and Development Center for Bioengineering (RDCB), Kragujevac. It is now in preparation the fifth volume of the JSSCM where papers are published in English and contributors are not only from Serbia, but also from all over the world. The Presidency of the SSCM considers that this journal is particularly important for young researchers in Serbia and is active to attract authors from other countries to publish in the JSSCM.
The SSCM is the founder of the research center RDCB where young talents (currently around 15) form Serbia are mainly involved in development of computational methods and software for bioengineering and engineering applications. Financial support comes through national grants of the Ministry of Science and Technological of Serbia, EU-grants, direct national and international contracts (e.g. University of Texas Medical Center at Houston). City of Kragujevac significantly supports the Center, providing space and the financial help.
Milos koJiC
President
thE italian Group oF Computational mEChaniCs (GimC) will held its biannual Conference in Syracuse (Sicily) on 22–24 September 2010. About 80 abstracts were received. General lecturers will be Nicolas Moes and Xavier Oliver. As a tradition, the conference is particularly addressed to young researchers. During the conference a price will be awarded to the two best Italian PhD theses in computational mechanics presented during the year 2009: httP://WWW.laMC.ing.uniBo.it/giMC2010/
23rd sEminar oF Computational Fluid dynamiCs organized by The CEA/DEN Saclay (French Atomic Energy Commission) and the SMAI/GAMNI (French Society for Applied and Industrial Mathematics) at the Institute Henri Poincare in Paris, January 24–25th 2011. More information:httP://WWW-MeCaFlu.Cea.Fr/
honom 2011 (EuropEan ConFErEnCE on hiGh ordEr nonlinEar numEriCal mEthods For partial diFFErEntial Equations), organized by Remi Abgrall (INRIA), Tito Toro (U. Trento), Claus-Dieter Munz (U. Stuttgart) and M. Dumbser (U. Trento) in Trento, (April 11–15, 2011). More information:httP://WWW.ing.unitn.it/~toroe/Files/honoM2011.PdF
7th GraCm intErnational ConGrEss on Computational mEChaniCs, Athens, Greece, 30 June–2 July 2011 organised by the Greek Association of Computational Mechanics (GRACM - www.gracm.ntua.gr) will be held in Athens, Greece, 30 June–2 July 2011. Established and emerging areas of computational mechanics are covered in the conference themes. Among the latter are multiscale modeling and simulation, bio-mechanics and computational materials science. Young researchers are encouraged to present their work. Special young investigator sessions will be organized and reduced fees are offered for this purpose. This is a novelty of the present meeting.
The conference co-chairmen: A.G. Boudouvis, National Technical University of Athens, GRACM President, G.E. Stavroulakis, Technical University of Crete, GRACM Vice-President.
Deadlines: 15 December 2010 Abstract submission. 15 February 2011 Acceptance notification. 15 March 2011 Full paper submission and early bird registration deadline.
Further and updated information as well as instructions for the abstract and paper format can be found in the conference website: httP://WWW.7graCM.ntua.gr
announCEmEnts
