ansys fluent 16.0 preview 4 -...
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© 2011 ANSYS, Inc. September 19, 2014 1
ANSYS FLUENT 16.0 Preview 4
© 2011 ANSYS, Inc. September 19, 2014 2
Parallel/HPC
© 2011 ANSYS, Inc. September 19, 2014 3
HDF5-Based Case/Data IO
• HDF5-based case/data file IO is introduced in R16.0
• Fully supports parallel IO for case/data read/write
• Sectioned data compression is implemented natively through HDF5
• Provides different modes of IO capability:
1. Host : only host does the IO, and data are collected or distributed
2. Node0: only node0 does IO, skipping the communication overhead with host
3. Parallel independent: all nodes fully parallel independent IO
4. Parallel collective: all nodes do IO collectively
© 2011 ANSYS, Inc. September 19, 2014 4
HDF5 IO Interface
• Fluent recognizes the .h5 suffix
• TUI for basic read/write:
• read-case box.cas.h5
• read-data box.dat.h5
• write-case box.cas.h5
• write-data box.dat.h5
• TUI for further options:
• /file/hdfio-options>
• compression-level
• io-mode
GUI for read/write
© 2011 ANSYS, Inc. September 19, 2014 5
HDF5 IO Performance
Node ZeroParallel
IndependentLegacy
16 9.6 8.8 11.21
32 8.5 7.7 10.44
02468
1012
Tim
e in
se
con
ds
sedan_4m case read
Node ZeroParallel
IndependentLegacy
16 2.2 1.6 21.3
32 1.9 1.3 24
05
1015202530
Tim
e in
se
con
ds
sedan_4m case write
Node ZeroParallel
IndependentLegacy
16 1.4 0.8 2.3
32 1.4 0.7 2.3
0
0.5
1
1.5
2
2.5
Tim
e in
se
con
ds
sedan_4m data read
Node ZeroParallel
IndependentLegacy
16 2.2 1.8 5.8
32 2.1 1.8 4.8
01234567
Tim
e in
se
con
ds
sedan_4m data write
© 2011 ANSYS, Inc. September 19, 2014 6
HDF5 IO Performance
Caseread
Dataread
Casewrite
Datawrite
Legacy 39.2 35.6 92.8 35.3
Parallel collective 25.5 8.2 56.4 26.2
0
10
20
30
40
50
60
70
80
90
100
Tim
e in
se
con
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LM6000_46M
Caseread
Dataread
Casewrite
Datawrite
Legacy 595.464 77.279 496.223 84.11
Par collective 300.14 56.27 431.983 80.6087
0
100
200
300
400
500
600
700
Tim
e in
se
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ds
HEXCORE_400M t512 t1024
© 2011 ANSYS, Inc. September 19, 2014 7
• Optimized communication algorithms
• Implemented multithreaded calculation
• Wall distance computations now scale better at high core counts (even 1024 and above)
• Speed ups simulations using enhanced wall treatments or turbulence models like SST
Wall Distance Computation Speedup
0
100
200
300
400
500
600
96x 192xTim
e fo
r so
luti
on
init
ializ
atio
n (
s)
Core count
R15
R16
Time taken in solution initialization of a 140M F1 benchmark case
© 2011 ANSYS, Inc. September 19, 2014 8
• Can now export a multi-grid FV file so customers can now post process using parallel FieldView session
• FV export now scales better than before
• Simulations with frequent FV exports benefit by this performance improvement
Multi-Grid FieldView Export
0
100
200
300
400
500
600
96x
Tim
e f
or
FV e
xpo
rt (
s)
Core count
R15
R16
Time taken to export 16 fields + 3 velocities for 111M truck case
© 2011 ANSYS, Inc. September 19, 2014 9
• Improvement of accuracy of node-based gradients in the presence of mesh interfaces
– Minimizes/eliminates residual jump at restarts
– Helps convergence of node-based gradient cases with mesh interfaces
Node-Based Gradients & Mesh Interfaces Accuracy Improvement
SAS Term for a 2D case with mesh interface in the middle
without special treatment
with special treatment
© 2011 ANSYS, Inc. September 19, 2014 10
• Helps performance of cases requiring edge information, e.g. shells and adaption
• Helps improve performance and scalability at high core counts
Improvement in Neighbor Edge Filling Algorithm
© 2011 ANSYS, Inc. September 19, 2014 11
• Partitioning based on grouping by Laplace coefficients – This avoids partition interfaces through high cell aspect ratio areas
– It improves convergence for cases with highly stretched cells
Laplace Partitioning
© 2011 ANSYS, Inc. September 19, 2014 12
AMG GPGPU Options
• Per equation user controls for AMG-GPGPU parameters
© 2011 ANSYS, Inc. September 19, 2014 13
Parallel Check
• Checks for system usage, interconnect speeds and load balance
© 2011 ANSYS, Inc. September 19, 2014 14
Other Parallel Enhancements
• Improved robustness for parallel solver
– Automatic handling of AMG divergence
• Cache flush
– Automatically checks for cache file buildup and warns users of potential performance impact
– New flag “-cflush” added to perform cache flush and restore the memory
• Results in more consistent and improved performance in affected cases
© 2011 ANSYS, Inc. September 19, 2014 15
Platform and Protocol Support
• CISCO usNIC
– Added support for newer CISCO usNIC protocol over Ethernet (an offering from CISCO to compete with Infiniband)
– usNIC has a latency of 2.3 us
– usNIC is currently supported by OpenMPI only
• MPI Upgrades
– Both Platform (IBM) and Intel MPI libraries are upgraded to latest versions (which has resolutions for some of the bugs encountered in earlier versions)
• Upgraded IBM-MPI to 9.1.2
• Upgraded Intel-MPI to 4.1.3
– For distributed mode runs, now ssh is used as default as it is more secure compared to rsh (rsh is still provided as an option)
© 2011 ANSYS, Inc. September 19, 2014 16
Platform and Protocol Support
• 64-bit integer support for Windows platform
– 64-bit integer support is added to be able to solve very large cases on Windows platform
• Intel v14.0 compiler upgrade for both Linux and Windows platforms
– Currently evaluation of latest Intel v14.0 compiler is underway.
– This complier has support for AVX2, Intel Haswell chips and Intel Xeon Phi
© 2011 ANSYS, Inc. September 19, 2014 17
Numerics
© 2011 ANSYS, Inc. September 19, 2014 18
Flow Forcing Boundary Condition
• New transparent flow forcing BC allows for correct modeling of transient wave dynamics
– Removes artificial reflection of outgoing waves from the boundary, allowing incoming waves to come into the domain
• Artificial reflection can be twice as big as the incoming wave
• Incoming waves are specified using a time-dependent profile or a UDF at non-reflecting boundaries
– Allows the use of smaller computational domains for transient flows
– Benefits combustion dynamics and transient external aero auto applications
• Notes:
– Available only in the pressure-based solver
– Incompatible with steady state flow, multiphase and compressible liquid models
© 2011 ANSYS, Inc. September 19, 2014 19
Flow Forcing Boundary Condition
• Right propagating wave in a pipe with an open end
• Incoming wave specified at the velocity-inlet on the left end
• Pressure-outlet at the right end
Comparison with 1D analytic solution
Transparent forcing Standard v-inlet BC NRBC
© 2011 ANSYS, Inc. September 19, 2014 20
Average Pressure Specification
• Average Pressure Specification at Pressure Boundary – Allows the exit pressure to vary across the boundary, but maintains
an average equivalent to the specified exit pressure value
– The Average Pressure Specification option now can also be used with Pressure profile(Radial or Axial) or Radial Equilibrium Pressure Distribution option
– Less reflective than previous version and improved results
– Benefits turbomachinery applications
• Important limitations and concerns – Pressure blending factor ‘f’ (default value 0.0) may need to change
f > 0.0 in cases where stability is degraded
– Not available with multiphase flows
© 2011 ANSYS, Inc. September 19, 2014 21
2D Blade Passage(PBNS)
f = 0.0 f = 0.5 (old)
Where ‘f’ is Pressure Blending factor, f = 0(default) recovers the fully averaged pressure, f = 1 recovers the specified pressure
This is because of the shock reflections from the outlet boundary
© 2011 ANSYS, Inc. September 19, 2014 22
Whites Case (DBNS)
f = 0.0 f = 0.5
Significantly more reflections, compare to results with value f = 0.0
These two example shows that, the pressure variation allowed in this boundary implementation slightly diminishes the reflectivity of the boundary as compared with the default ‘Constant Pressure Specification’ or when f = 0.5 is used as pressure blending factor
© 2011 ANSYS, Inc. September 19, 2014 23
3D Goldman Stator (DBNS)
bin avg pressure Specified profile on bin In this example exit pressure is specified as
radial Profile and Average Pressure Specification option is used. Contour plot shows the pressure variation at the outlet boundary, however averaged value of pressure matches closely with the specified pressure profiles on bins(see XY-Plot).
© 2011 ANSYS, Inc. September 19, 2014 24
Poor Mesh Numerics
• Criteria for marking of poor elements – Default (ON, No user control) : Cells with negative volume, non-convex
cells, cells with left handed faces
– Cell Quality Based (User choice) : Cells with low orthogonal quality
– User Defined : User’s own criteria
• Improves specification of cell-based quality criterion for marking bad elements, which in turn provides better robustness
• Text user interface has also been improved
© 2011 ANSYS, Inc. September 19, 2014 25
Poor Mesh Numerics Improvements
Equiangle Skewness
Orthogonal Quality
Old Criterion
New Criterion
© 2011 ANSYS, Inc. September 19, 2014 26
Improved text user interface
Poor Mesh Numerics Improvements
© 2011 ANSYS, Inc. September 19, 2014 27
Jet Impingement over Flat Plate
Problematic case : - Diverged without poor mesh numerics
irrespective of solver settings - Diverged with poor mesh numerics
treatment in R15 - Smooth convergence with improved poor
mesh numerics treatment in R16.0
© 2011 ANSYS, Inc. September 19, 2014 28
Compressible Flow Numerics Improvements
• Extension of work done at R15 – Treatment for SIMPLEC, PISO
– Treatment for user-defined compressible gas/liquid
– Treatment for multiphase flow
• Objective is to improve robustness for compressible flow simulations by controlling the rate of change of pressure and temperature within iterations and also by increasing diagonal dominance for coupled solver
• Final solution is not changed, only the convergence behavior
© 2011 ANSYS, Inc. September 19, 2014 29
Enhanced Compressible Numerics
• Improved start-up and run-time robustness for compressible multiphase flows
Eulerian Multiphase Mixture Multiphase VOF
© 2011 ANSYS, Inc. September 19, 2014 30
• Beta in R15.0, now full feature
– Impedance Boundary Conditions can model the impact of pressure reflections from outside the domain of interest on the domain of interest without including those zones in the simulation
1-D Wave at a boundary
• L=1m, dx=0.01, N=100
• Inlet Pt=58.6 pa, Tt=300 K, u=10 m/s
• Gaussian wave (FWHM=0.125, 30 points), 154 Db, 1e3 Pa
Impedance Boundary Condition
IBC, R=0 IBC, R=-1 IBC, R=-0.5
© 2011 ANSYS, Inc. September 19, 2014 31
Improved Rothalpy Transport
• Improved Rothalpy Transport
– Aims to accurately compute viscous heating at the interface between two frames of references with the relative velocity formulation
– Important for turbomachinery applications
© 2011 ANSYS, Inc. September 19, 2014 32
Improved Rolthapy Transport
• Results for Axial Turbine
0
20
40
60
80
100
120
3000 rpm 3500 rpm 4000 rpm 4500 rpm 5000 rpm 5500 rpm
Cm-Abs
Cm-relative-Legacy
Cm-Relative-R16.0
Cm
© 2011 ANSYS, Inc. September 19, 2014 33
Improved Rothalpy Transport
1.35
1.36
1.37
1.38
1.39
1.4
1.41
1.42
1.43
1.44
1.45
3000 rpm 3500 rpm 4000 rpm 4500 rpm 5000 rpm 5500 rpm
MF-Abs
MF-relative-Legacy
MF-Relative-R16.0
Mass Flow Rate
280
285
290
295
300
305
310
3000 rpm 3500 rpm 4000 rpm 4500 rpm 5000 rpm 5500 rpm
To-Abs
To-Relative-Legacy
To-Relative-R16.0
Total Temperature at Stator 2 Exit
© 2011 ANSYS, Inc. September 19, 2014 34
Improved Shock Capture
• Roe flux method has been added as an option for the pressure-based solver
– Improves the resolution of shock waves
• Requires only half the cells needed by the traditional Rhie-Chow method
– Benefits external and internal aerodynamic simulations with shocks
BETA
© 2011 ANSYS, Inc. September 19, 2014 35
Improved Shock Capture
• Results for air foil simulation
– Mach number 0.8, angle of attach 4 degrees
– Spalart-Allmaras turbulence model
• Shock wave on the upper side is further downstream with Roe flux in PBNS compared with Rhie Chow flux, better matching the DBNS results
Comparison with Rhie-Chow flux Comparison with DBNS
BETA
© 2011 ANSYS, Inc. September 19, 2014 36
Non-Reflecting BC with VOF
• Non-Reflecting BC is now compatible with VOF at pressure outlets
– Eliminates artificial reflection from the boundary
– Transient VOF droplets, mixture applications, in particular, will benefit
BETA
© 2011 ANSYS, Inc. September 19, 2014 37
Non-Reflecting BC with VOF
• Results for simulation of droplet motion in a pipe
– Inlet flow forcing in a pipe, mean flow: u = 100 m/s
– Velocity-inlet at left with u = 100(1+0.15sin(2pi 1000 t) sets up a right propagating wave on top of mean flow
– Pressure-outlet at right
– VOF with two phases (secondary phase: droplet r=15mm)
NRBC No NRBC
BETA
© 2011 ANSYS, Inc. September 19, 2014 38
Turbulence
© 2011 ANSYS, Inc. September 19, 2014 39
Turbulence Modeling Improvements
• Speed improvements of SST model
• BSL-w model implementation in Fluent
– Robust general-purpose model which will be the basis of our w-equation based turbulence modelling strategy
• To serve as replacement for RKE
• Basis for EARSM and RSM
• Combined all models with transition, rough walls etc.
• Improvement for Scale-Resolving Simulations (SRS)
– Extension of SRS models to polyhedral cells
• Some of our model use the maximum edge length – this is not suitable in poly meshes, as it does not reflect the size of such cells. Now using a more generic formulation which is backwards compatible with current formulation
© 2011 ANSYS, Inc. September 19, 2014 40
Turbulence Modeling Improvements
• Default change – WALE model default for LES
– WALE model offers best ratio of complexity and accuracy
• SAS + Rough walls
– allow combination of both model options
• Consolidate definition of turbulence length scale Lt across codes (was different in Fluent)
• Allow combination of Enhanced Wall Treatment with rough walls
• Implement some missing hooks for user-specified Prandtl/Schmidt numbers
• Change default inlet value for Spalart-Allmaras model
• Allow combination of Enhanced Wall Treatment with rough walls BETA
© 2011 ANSYS, Inc. September 19, 2014 41
Stress-Blended Eddy Simulation (SBES)
• New Scale-Resolving Simulation Option
– Separation of RANS, LES and blending
– Separately select a RANS and a LES model in a building block approach
– Visualize the regions where the RANS and where the LES models are active
– Flexibly select RANS and LES zones using UDFs in a zonal fashion
– Can mimic all existing models (WMLES, DDES, DES, …)
– Can provide perfect shielding of BL
Round jet at M=0.9 and Re=1.3 106 : 3D structures are obtained almost immediately downstream of the nozzle.
LES
ij
RANS
ijij ff 1
BETA
© 2011 ANSYS, Inc. September 19, 2014 42
Acoustics
© 2011 ANSYS, Inc. September 19, 2014 43
Frequency Band Post Processing
• Frequency band post processing of sound sources – FFT of transient surface pressure fields
– User creates/removes variables for visualization:
• SPL (surface pressure level, in dB) for frequency bands
• Octaves, 1/3-octaves, user-defined bands
• Fourier amplitudes for single selected modes
• Flexible memory control, other service functionality
© 2011 ANSYS, Inc. September 19, 2014 44
CGNS Export of Pressure Spectra
• 1-way coupling to ANSYS Mechanical in frequency domain – Scale-resolving transient simulation is performed in Fluent and
pressure histories are exported from a coupling wall zone
– New: FFT of wall pressure field -> exported in CGNS files
– CGNS files are inputs for harmonic and response analysis in ANSYS Mechanical
• Vibration and acoustics for different frequencies
• Targeted at the automotive industry – Cabin noise from external turbulent flow
BETA
© 2011 ANSYS, Inc. September 19, 2014 45
CGNS Export of Pressure Spectra
• Geometry and Fluent results for car cabin noise example
U = 40
m/s
Fluent domain
ANSYS Mechanical domain (closed box)
“Side mirror”
Resolved separated flow
BETA
© 2011 ANSYS, Inc. September 19, 2014 46
CGNS Export of Pressure Spectra
• ANSYS Mechanical results for car cabin noise example: Plate displacement at 20 Hz, 70 Hz, 500 Hz
• Microphone sound spectrum in the cavity center, SPL( f ) for 20 Hz – 500 Hz
Sound pressure level
BETA
© 2011 ANSYS, Inc. September 19, 2014 47
Discrete Phase Model (DPM)
© 2011 ANSYS, Inc. September 19, 2014 48
Wall Film Model Improvements
• Impingement and Splashing UDF – Allows customization of wall-film particle behavior for spray-wall
interaction applications
– Provides several UDF hooks for Lagrangian wall film model
• Specify an impingement regime
• Set particle variables for a regime
• Customize diameter, velocity distributions for splashed particles
– Benefits aerospace and automotive industries
• Gas turbine and automotive fuel injectors application, in particular, will benefit
© 2011 ANSYS, Inc. September 19, 2014 49
Impingement and Splashing UDF
O’Rourke/Amsden impingement model (default)
User Defined film behavior for high impact on hot walls (UDF)
© 2011 ANSYS, Inc. September 19, 2014 50
Wall Film Model Improvements
• Energy transfer from Lagrangian film to the wall – Refactoring of wall film temperature solution now allows for direct
transfer of energy to wall covered by the film
– Provides increased accuracy for all simulations using Lagrangian wall film
– Compatible with all thermal boundary conditions and all particle types usable in the wall film
– Note: Radiation effects are not accounted for
© 2011 ANSYS, Inc. September 19, 2014 51
Wall Film Model Improvements
• New film boiling model for droplet and multi component Lagrangian film particles
– Boiling rate is now computed directly from solution of particle energy equation- includes impact of chosen boundary condition of the wall covered by the film
– Allows a larger range of applications of the Lagrangian wall film at an increased accuracy (before the particle temperature was just limited by its boiling temperature)
– Note: Radiation effects are not accounted for
© 2011 ANSYS, Inc. September 19, 2014 52
Heat Transfer to Walls
• Heat transfer from particles to walls can now be accounted for
– When a liquid particle is in contact with a wall it can exchange heat with the wall for the time of contact- the heat exchange is considered in the particle as well as on the wall
– Previously, particles were considered adiabatic when reflected at a wall
– Supported with reflect, wall-jet, or wall-film boundary conditions
– Allows for new applications where heat transfer of particles to walls is important
– Note: Cannot be used within the DDPM framework
© 2011 ANSYS, Inc. September 19, 2014 53
Parallel Reproducibility
• New random number generator – Helps users to reproduce tracks as displayed in serial in a parallel run
– Consistent and unique seeding across all but volume injection types
– Provides unique particle ids in serial and parallel to increase reproducibility in serial and parallel
© 2011 ANSYS, Inc. September 19, 2014 54
Parallel Scalability
• Extend hybrid parallel tracking to non-adiabatic non/partially-premixed combustion model – Non-adiabatic non/partially-premixed combustion model can now take
advantage of hybrid parallel tracking (before this was disabled internally)
– Users of these model combinations will see improved speedup and scalability
© 2011 ANSYS, Inc. September 19, 2014 55
Binary Diffusivity
• DPM binary diffusivity of evaporating species is now dependent on pressure and temperature – Previously, it was only dependent on temperature
– Benefits applications where the pressure dependency is important such as piston engines and gas turbine atomizers
© 2011 ANSYS, Inc. September 19, 2014 56
Discrete Phase Particle Rotation
• The effect of particle rotation can now be considered with the DPM model
– Including rotational drag forces and lift forces
– Considering impact during wall reflection
– More accurate results for solid particle simulations in wall-bounded flows
BETA
© 2011 ANSYS, Inc. September 19, 2014 57
Dense Phase Particle Rotation
• The effect of particle rotation can now be considered with the DEM model – Including rotational forces during contact evaluation
– Makes the DEM model applicable to a wider range of applications
BETA
© 2011 ANSYS, Inc. September 19, 2014 58
Reacting Flows
© 2011 ANSYS, Inc. September 19, 2014 59
New Equilibrium Solver
• New Equilibrium Solver CEQ is implemented – This replaces existing equilibrium solver CPROP
– CPROP fails in performing equilibrium calculations for many applications such as EGR, Diesel Unsteady Flamelets
– CEQ is more robust, fast and accurate
© 2011 ANSYS, Inc. September 19, 2014 60
Soot Model UDF Hooks
• Generalized Soot Model – User can implement their own soot models through this functionality
– The udfs can be provided for each subcomponents of soot model like
• Nucleation, Coagulation
• Surface growth, oxidation
– Fully flexible and has options for adding/replacing the Fluent’s default
– In conjunction with PDF model, it allows to pre-tabulate the soot rates in PDF tables
– Can handle the turbulence chemistry interactions like default models
© 2011 ANSYS, Inc. September 19, 2014 61
Finite Rate Chemistry Speed-Up
• Several improvements to improve performance – Replaced sundials with CVODE for ISAT
– Enhancements in the ODE solver performance
– Reaction rates solver improvements
– ISAT optimization
– ODE solver tolerance optimization
– R16 will be much faster than R15 for finite rate chemistry
• All applications that require finite rate chemistry modeling will benefit
© 2011 ANSYS, Inc. September 19, 2014 62
• New Method of Moments soot model
– Interpolative closure for soot diameter and surface area
– Moment transport equations solved in Fluent
– Moment source terms consider realistic chemical and physical processes
– Coupled to the flow through radiation heat transfer
• May be at R16 - TBD
New Soot model
BETA
© 2011 ANSYS, Inc. September 19, 2014 63
Other Reacting Flow Improvements
• Real gas enhancements: NIST 9.1 update (this was beta in R15)
• Support encrypted mechanisms for Chemkin-CFD
– Available for Chemkin-CFD and other Fluent models:
• Can be used with relax to equilibrium or laminar stiff chemistry
• Surface chemistry is not supported
• Flamelet generation is only serial
• DMR and DR are not supported
© 2011 ANSYS, Inc. September 19, 2014 64
Radiation & Heat Transfer
© 2011 ANSYS, Inc. September 19, 2014 65
Surface-to-Surface Radiation
• S2S Model Performance
– Improved performance with non-conformal interfaces
• No need to encapsulate coupled wall faces at partition interface
• Better overall load balance (in parallel)
• Significantly improves solver time (i.e. time/iteration)
• Up to 10X faster for (for >64 cores)
– Faster view factor computation for poly meshes with ray tracing method
• No further triangulation needed
• View factor computation for 884K poly mesh is 8-10X faster in R160
– Improved I/O with binary file format support
• Faster reading of view factor file- up to 4x faster in testing
• Writing supported on linux64 only
• Files written on linux64 can be read on win 64
– Particularly beneficial for underhood applications
© 2011 ANSYS, Inc. September 19, 2014 66
Performance Gain with Further Optimization
0
5
10
15
20
25
t8 t16 t32 t64 t128
R160-New
R150
Solver Time Per Iteration
Number of Cores
© 2011 ANSYS, Inc. September 19, 2014 67
Multi-Layer Shell Conduction
• Faster I/O and solver time for shell conduction
– Significantly improved case read time and solver time (i.e. time/iteration)
• New UDF hook for heat generation rate
– Allows users to specify profile of heat generation in their simulations
Case read time vs CPUs Solver time per iteration vs CPUs
© 2011 ANSYS, Inc. September 19, 2014 68
Other Radiation & Heat Transfer Improvements
• Mapped meshes for CHT modeling – Allows thermal coupling between (indirect) mapped mesh interfaces
– May be at R16 – TBD
• Anisotropic thermal conductivity – Allows users to specify principal values and axes for anisotropic
thermal conductivity
BETA
© 2011 ANSYS, Inc. September 19, 2014 69
Mesh Morpher and Optimization (MMO)
© 2011 ANSYS, Inc. September 19, 2014 70
MMO Control Points Improvements
• MMO has multiple options to specify control points on the surface of any boundary for improved control over movement of surface mesh node – Including the ability to:
• Specify the control points (e.g. mouse control, XYX coordinates, etc.)
• Specify the parametric motion definitions (translation, rotation, radial)
• Display the control points
– Access to both structured (available with previous releases) as well as unstructured control point specifications (new at R16.0)
© 2011 ANSYS, Inc. September 19, 2014 71
Surface Morphing User Interface
© 2011 ANSYS, Inc. September 19, 2014 72
Mesh Deformation Using Mouse Probe
Mouse probe can be used to selectively move the internal control points and thus adjacent mesh nodes more accurately
© 2011 ANSYS, Inc. September 19, 2014 73
Multiphase
© 2011 ANSYS, Inc. September 19, 2014 74
Multiphase Species Mass Transfer
• Multiphase mass transfer laws – Mass transfer processes are modeled using distribution laws- three
such laws have been implemented in Fluent:
• Henry’s Law (Gas-Liquid)
• Raoult’s Law (Ideal Solution)
• Equilibrium Ratio model (Non-Ideal Solution)
– Benefits challenging multicomponent multiphase problems often encountered in chemical and petrochemical industries
• DAF tanks, bioreactors, distillation columns/trays
© 2011 ANSYS, Inc. September 19, 2014 75
Coupled Level Set Improvement
• Coupled Level Set Improvement
– Reduces Spurious currents from surface tension dominated low velocity flows
– Useful for surface tension dominated flow, micro fluidics
© 2011 ANSYS, Inc. September 19, 2014 76
PVT Lookup Table
• Ability to use a lookup table with the NIST real gas model to specify phase properties as a function of PVT
– Less expensive (much faster) than using the NIST model directly
– Required to solver problems involving condensation, evaporation, flash evaporation (single component) and to perform high fidelity oil and gas reservoir simulations
© 2011 ANSYS, Inc. September 19, 2014 77
Multiphase in Porous Media
• Multiphase flow in porous media can be modeled – Based on the full Navier-Stokes equations
– Takes into account:
• Relative permeability of the different phases
• Relative viscosity between phases
• Capillary pressure
– Models for relative permeability are:
• Cory-Brooks model for two-phase simulations
• Stone I and Stone II for three phase simulations
BETA
© 2011 ANSYS, Inc. September 19, 2014 78
Other Multiphase Improvements
• NITA (Non-Iterative Transient Advancement) is now available for multiphase flows
– Significant speed up for all transient Eulerian multiphase simulations
• More robust modeling of mixing tanks and bubble column separators
– Implicit treatment of the virtual mass force
– Nphase continuity solver
• Computes the solution of continuity equations for all phases
• Reduces mass imbalance problems that commonly occur in with these simulations
• Flow regime transition model
– Captures the dynamic flow regime transitions for two-phase gas-liquid flow
– Developed within the framework of the VOF and multifluid VOF model
– Useful for simulating glows in vertical risers, oil wells and pipelines
© 2011 ANSYS, Inc. September 19, 2014 79
VOF and Multi-Fluid VOF Restructuring
• New option to choose interface modeling type
– Available discretization schemes and drag laws based on interface modeling type
– Allows for more intuitive set up and helps avoid user errors
Interface Modeling Type
Implicit Formulation Explicit Formulation
Sharp Compressive (default) HRIC, BGM
Geo-Reconstruct (default) CICSAM, Compressive, HRIC
Sharp/Dispersed Compressive (default) Modified HRIC
Dispersed 1st order upwind (default) Second order upwind Quick
1st order upwind (default) Quick
Interface Modeling Type
Drag Laws for Multi-Fluid VOF
Sharp Symmetric, Anisotropic
Sharp/Dispersed All the drag laws available
Dispersed All the drag laws but Anisotropic
© 2011 ANSYS, Inc. September 19, 2014 80
Free Surface Options
• Free surface regime modeling options
– Options to address cases where interface modeling may depend on cell zone or phase pair
• Zonal discretization
• Phase localized discretization
• Free surface expert options
– Sub-time step calculation method
– Solve VOF every iteration
© 2011 ANSYS, Inc. September 19, 2014 81
• Generalized variant of compressive scheme has been developed – Applicable to both Sharp and Dispersed regimes.
– Adaptive: produces desired behavior depending on the regime type (Sharp, Dispersed and Sharp/Dispersed)
– Bounded: an improvement over the HRIC/R15-compressive for dispersed flow regimes
• New default for sharp/dispersed regime type
• Default unchanged for sharp regime
• Crucial for flow regime modeling in oil & gas industry
Modified Compressive Scheme
© 2011 ANSYS, Inc. September 19, 2014 82
Straight pipe with liquid VOF=0.5 at the inlet. The modified compressive scheme ensures the boundedness compared to other schemes.
Modified Compressive Scheme in Dispersed Regime
Compressive Modified Compressive
CICSAM HRIC
Max vof = 0.654 Max vof = 0.58
Max vof = 0.98 Max vof = 0.5
© 2011 ANSYS, Inc. September 19, 2014 83
Modified compressive scheme also works very well for a sharp regime Images below show comparison of modified compressive (red curves) vs compressive (white curves)
Modified Compressive Scheme in Sharp Interfacial Regime
Slotted circle after one rotation Wigley Hull
© 2011 ANSYS, Inc. September 19, 2014 84
Slurry (Water + Solids)
Gas bubble
Phase Localized Compressive Discretization • Bubble & Slurry
• Max Slope Limiter Beta= 2 • This is Compressive/Modified
Compressive • Slurry (Water & Solids):
• Max Slope Limiter Beta = 0 or 1 • First order (0) or second order (1)
Contours of Solid Volume Fraction
Beta (2,0) Beta (2,1) Beta (2,1)
With standard compressive
With modified compressive
Unphysical sharpening of solids
Modified compressive shows appropriate settling of solids
Modified Compressive Scheme in Sharp Interfacial Regime
© 2011 ANSYS, Inc. September 19, 2014 85
• Available with VOF and Eulerian multiphase with multi-fluid VOF option – Feature was available with Explicit
formulation- it has been extended to implicit formulation
• Will help estimate proper time step size for implicit VOF calculation and will speed up the transient calculations
Variable Time Stepping for Implicit VOF
© 2011 ANSYS, Inc. September 19, 2014 86
Random Wave Modeling Using Wave Spectrum
• Various frequency/directional spectrum methods are available
– Frequency Spectrums
• Pierson-Moskowitz Spectrum
• Jonswap Spectrum
• TMA Spectrum
– Directional spectrum
• Cosine (frequency independent)
• Hyperbolic (frequency dependent)
• Wave check capability
• Critical for marine industry: ship design, oil skimming
Longitudinal/frequency dependent Frequency + Direction Dependent
© 2011 ANSYS, Inc. September 19, 2014 87
Random Wave Modeling Using Wave Spectrum
Long-Crested Unidirectional
Short-Crested
© 2011 ANSYS, Inc. September 19, 2014 88
• New treatment allows better accuracy and robustness in case of negative absolute pressures
• Recommended for all MDM and high pressure applications
Case study: Water Hammer
Pipe flow with steady state profiles is suddenly closed at one end, which produces water hammer effect.
Average pressure at outlet accurately predicted using the new improvements
Compressible Liquid Improvements
© 2011 ANSYS, Inc. September 19, 2014 89
VOF Initialization Options
With Patch
With Patch and Smoothing
• New volume fraction patch options to minimize start up instabilities
– Patch reconstructed interface
– Volumetric smooth
© 2011 ANSYS, Inc. September 19, 2014 90
• Mass transfer improvements with explicit VOF for constant mass transfer rate specification
• Phase-specific surface monitors/reporting for VOF and Mixture models
Other Multiphase Modeling Enhancements
Monitors
Reporting
© 2011 ANSYS, Inc. September 19, 2014 91
VOF Interface Accuracy for Poor Mesh
• New option to model interfacial anti-diffusion improves interfacial accuracy for sharp interfaces with the following mesh scenarios – Coarser mesh
– High aspect ratio
– Mesh with large cell volume jump
– Cut-Cell mesh
– Polyhedral mesh
– Skewed mesh
© 2011 ANSYS, Inc. September 19, 2014 92
Interface Capturing Comparisons
with interfacial anti-diffusion
without interfacial anti-diffusion
© 2011 ANSYS, Inc. September 19, 2014 93
Interface Capturing Comparisons
with interfacial anti-diffusion
without interfacial anti-diffusion
© 2011 ANSYS, Inc. September 19, 2014 94
VOF Case Check Summary
• Summarizes case setup and provides additional recommendations
• Verbosity option: 0 (compact) or 1 (detailed)
• Summary is printed on Fluent console
BETA
© 2011 ANSYS, Inc. September 19, 2014 95
Sample VOF Summary
• More details are printed below this
BETA
© 2011 ANSYS, Inc. September 19, 2014 96
Adjoint Solver
© 2011 ANSYS, Inc. September 19, 2014 97
Robust Solution of Large-Scale Problems
• New solution advancement scheme for the adjoint solver – Large-scale problems can be solved more robustly
– Successful simulation of external aerodynamic cases up 100M+ cells
© 2011 ANSYS, Inc. September 19, 2014 98
Automated Solution Advancement
• An automated solution advancement “expert system” for the adjoint solver has been developed – Significantly reduces the challenges associated with solving adjoint
problems
– In R15 and earlier the user had to select settings such as Courant number etc., based on how the adjoint solution was advancing
• This made it challenging in many cases for non-expert users to get solutions without help.
– The new feature provides initial choices for settings and updates them dynamically as the adjoint calculation progresses
© 2011 ANSYS, Inc. September 19, 2014 99
Automated Solution Advancement
• External aerodynamic simulation of generic racer (half car, 15M cells)
• Drag sensitivity was computed
• Automated solution advancement provides a push-button solution for a problem that was previously been a challenge to solve
Adjoint Pressure Adjoint Residuals
© 2011 ANSYS, Inc. September 19, 2014 100
Volume Integral Observable
• Volume integral over a fluid zone or a Cartesian region can be specified as the observable
– Enables specialized questions to be asked about flow losses and wake structures
• Variety of integral types
– Volume integral, average and variance
– Mass integral, average and variance
– Sum
• Variety of integrand types
– Pressure and total pressure
– Vorticity
– Velocity magnitude
– Turbulence production
© 2011 ANSYS, Inc. September 19, 2014 101
Management of Design Changes
• New design tool provides much richer functionality than before and greater efficiency for mesh morphing
• Key extensions include: – Multi-objective design
– Prescribed design changes
– Freeform deformation
– Detailed control of the morphing
– Design conditions
– All of the above features can inter-operate!
© 2011 ANSYS, Inc. September 19, 2014 102
New Model Support
• Adjoint solver now supports: – Porous media relative velocity formulation
– User-defined sources (with the udf modified to be “adjoint-enabled”)
© 2011 ANSYS, Inc. September 19, 2014 103
Solver Meshing
© 2011 ANSYS, Inc. September 19, 2014 104
Mesh Interfaces
• Mapped interface option for coupled interfaces for fluid-fluid and fluid-solid
• Enabled usage of sided centroids at coupled interfaces – More accurate and more robust handling of penetrating mesh
interfaces
• Improved performance when deleting mesh interfaces during I/O
• More intuitive interface zone names
© 2011 ANSYS, Inc. September 19, 2014 105
Polyhedral Conversion
• Removed parallel bottleneck for meshes >> 50 million cells – Conversion time on 64 CPUs was reduced from 14.3 h to 1.7h for mesh
with > 100 million cells
• Option to preserve prismatic extrusion layer during conversion • Code will do analysis of input mesh to recommend enabling of
preservation
• Enables more robust conversion for very high aspect ratio meshes without cell count increase in extrusion layer
• Improved parallel performance of optimization step • Avoids encapsulation of very poor polyhedra during optimization
• Added TUI option to skip migration and reordering after conversion
© 2011 ANSYS, Inc. September 19, 2014 106
Other Solver Meshing Improvements
• Parallel zone remeshing – Makes it possible to remesh an entire zone without the overhead of
zone encapsulation on a single CPU
• Improved performance of dynamic mesh spring smoothing in parallel
© 2011 ANSYS, Inc. September 19, 2014 107
Miscellaneous
© 2011 ANSYS, Inc. September 19, 2014 108
System Coupling Improvements
• Porous jump support – Porous jump boundary condition can now be used for 1-way and 2-way
data FSI applications.
• Fluent sends nodal force and/pr consumes nodal displacement data via system coupling
• Deforming porous zones – Porous media can now be used for FSI applications
– Porous jump boundary (with thickness = 0) is used adjacent to porous zone to serve forces and receive displacements from system coupling
– May be at R16.0 - TBD
• Allow Fluent and Mechanical to be used to model filters via System Coupling
BETA
© 2011 ANSYS, Inc. September 19, 2014 109
System Coupling Improvements
• Fluent monitor data – All monitor data defined in Fluent can be tracked in System Coupling
• Residuals, statistics, forces, surface and volume monitors
• Monitor data is consistent with Fluent names
• Exchange heat flux/temperature at thermally coupled walls – Allows users to exchange heat flux/temperature values at coupled
walls from Fluent to MAPDL via System Coupling
– Avoids problems with convergence of thermal quantities at the FSI interface
– Displacements due to thermal stresses get passed back to Fluent
© 2011 ANSYS, Inc. September 19, 2014 110
Workbench Usability and Performance
Multiple upstream mesh systems
• Connect multiple upstream mesh components with Fluent's Setup cell
• Allows for parametric simulations where only part of domain requires re-meshing
© 2011 ANSYS, Inc. September 19, 2014 111
Workbench Parameters and Optimization
Context menu of the Mesh cell allows user to register Fluent Mesher Journal file. The journal is then executed automatically during Project update.
Parametric support for Fluent Meshing
• Parameter Manager in WB now supports Fluent Meshing
• Parametric journals are registered with Mesh cell and automatically executed during Project’s update
Fluent Meshing geometry connectivity
• Fluent Mesh cell can now receive geometry from upstream Geometry cell.
BETA
BETA
FLTG system connected to the upstream Geometry component. Parameters defined in Mesher journal are exposed and controlled in WB.
© 2011 ANSYS, Inc. September 19, 2014 112
Transient Convergence Monitoring
• Monitor number of iterations per time step
– Allows user to monitor the residual behavior in time
– Users can see which time steps converged quickly and which time steps took the maximum number of iterations in any transient simulation
© 2011 ANSYS, Inc. September 19, 2014 113
Monitoring Iterations per Time Step
not converging in these time steps
User can easily determine which time steps are not converging- this cannot be seen from the standard residual plot on the left
Standard Residuals Iterations per Time Step
© 2011 ANSYS, Inc. September 19, 2014 114
Surface Import
• New option to import surfaces for post-processing – Import a surface (in .stl or .msh
format) and create a post-processing surface
© 2011 ANSYS, Inc. September 19, 2014 115
Custom Vectors
• Custom vector capability for post-processing
– Three new options are available in the surface integrals panel:
• Custom Vector Based Flux (𝒗𝑐 , 𝜑) = 𝜑𝒗𝑐𝑓 ∙ 𝑨
• Custom Vector Based Flux (𝒗𝑐) = 𝒗𝑐𝑓 ∙ 𝑨
• Custom Vector Weighted Average
(𝒗𝑐 , 𝜑) = 𝒗𝑐∙ 𝑨 𝜑 𝑓
𝒗𝑐∙ 𝑨 𝑓
© 2011 ANSYS, Inc. September 19, 2014 116
New Tree-Based UI
• A new tree-based UI is introduced in R16
– The tree replaces the navigation pane
– All the previous navigation pane options are available in the tree
• Branches of the tree provide an overview of the case set up
• New right-click menus allow quick access to most commonly used functionality
© 2011 ANSYS, Inc. September 19, 2014 117
New Tree-Based UI
© 2011 ANSYS, Inc. September 19, 2014 118
Contour and Vector Objects
• Contour and vector definitions can be saved in and re-displayed from the tree
© 2011 ANSYS, Inc. September 19, 2014 119
Default Mesh Display Configurations
• Quick access to different ways of displaying the mesh
© 2011 ANSYS, Inc. September 19, 2014 120
3rd Party Tool Support
• Export of polyhedral cells to CGNS – Cases with polyhedral cells can now be exported in the CGNS format
• Support for export of surfaces in FieldView multigrid format – Domain export in multigrid format was already available in R15
• WAVE version upgraded to WAVE2014.1 – Support on linux64 and win64