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© CADFEM 2016

ANSYS CFD

Lionel Wilhelm, Joël Grognuz, Aniko Rakai

ANSYS CFD 1

© CADFEM 2016 ANSYS Discovery Live Webinar 2

13H30 Bienvenue

13H40 Simulation fluidique et productivité

• Résumé de l'état de la technique en simulation d'écoulements (exemples industriels) : multiphases, mélanges, particules, spray, réactions physico - chimiques, érosion - Interaction fluide structure (FSI) - Thermodynamique - Aéro-acoustique -Circuits, jumeaux numériques

• Choix de l'outil approprié: compromis entre précision et temps ingénieur

• Démos dans ANSYS: simulation transitoire instantanée sans maillage avec ANSYS Discovery Live - Fluent Water Tight Meshing Workflow (defeaturing géométrique ciblé, maillage mosaïque et simulation en un temps record)

15H00 Pause

15H30 EPFL – Laboratoire des machines hydrauliques

• A multiscale model for sediment impact erosion simulation using the finite volume particle method

Sebastian Leguizamon, EPFL Doctoral Student

• GPU-Accelerated 3-D finite volume particle method applied to pelton turbine flow simulations

Siamak Alimirzazadeh, EPFL Doctoral Student

• Vortex numerical simulations of Francis turbine at part load and deep part load operating conditions

Prof. François Avellan EPFL

16H30 Visite du laboratoire et des installations

17H00 Apéritif


© CADFEM 2016

FSI

© CADFEM 2016

Meshing Methods

•Goal:

Follow large deformations while ensuring

mesh quality

•Typical Methods

•Smoothing

method moves interior nodes to absorb the

motion of a moving/deforming boundary

•Remeshing

5ANSYS FSI, state of the art

© CADFEM 2016

Meshing Methods

Overset mesh (no remeshing required):

overset interfaces

connect cell zones by

interpolating cell data in

the overlapping regions


© CADFEM 2016

Custom Mesh methods

ANSYS FSI, state of the art 8

© CADFEM 2016

Vortex-Induced Fluid-Structure Interaction (time domain)

- 11 /

13-

Source: Kalmbach, M. Breuer, Complementary

Experimental and Numerical Investigations on a New

Vortex-Induced Fluid-Structure Interaction Benchmark (FSI-

PfS-2a), A. Helmut-Schmidt-Universität Hamburg,

proceedings, ANSYS CADFEM Users Meeting, 2013

© CADFEM 2016

Tetra Pack


© CADFEM 2016

FSI

Update ANSYS 15.0 - Roadshow 14

1) Non deformed

geometry

4) Fluid Structure

Interaction

2) Stent Pre-stress

3) Stent positioning inside

aorta and binding to valve

Source: Walid M. Hassan (May-Jun 2010) Ann Saudi Med. 30(3): 183–186.

© CADFEM 2016

PET bottle crash test


© CADFEM 2016

Other FSI approaches: Rigid Bodies

• Simpler FSI approaches are possible when simplifying assumptions can be made

• If the solid moves but does not deform (rigid body), then a 6-Degree of Freedom rigid body solver can be used

• Rotation about 3 axes, translation along 3 axes = 6 DOF

• More efficient than using a full FEA solver

• No structural solution field

• Examples: Boats in waves, falling objects


© CADFEM 2016

Mesh Deformation and Fluid-Structure-Interaction

• Eulerian explicit (FEM)

Aquaplaning

© CADFEM 2016

…on the rocks!


© CADFEM 2016

Lagrange DEM particles without fluid

• Complex Motions: 6 Degrees of Freedom (DOF)

Hinged flop gate free to rotate about the Z axis.

Displacement and wear rate also captured.


© CADFEM 2016

Lagrange DEM “particles” without fluid

• Screening / Sorting

© CADFEM 2016

Other FSI approaches: many rigid bodies (no CFD)

Discrete Element Modeling (DEM)

• DEM –> FEM coupling

Rocky

ANSYS Mechanical

Fluid behaviour?


© CADFEM 2016

combining fibers, shells and solids

© CADFEM 2016

Flexible fibers with CFD coupling

© CADFEM 2016

Flexible fiber: accurate stress-strain response

© CADFEM 2016

Pipe separator (Lagrange DEM – Euler CFD)

• Rocky-Fluent

One-way coupling example: waste separator Two-way coupling example: fluidized bed



© CADFEM 2016

Acoustics

ANSYS Discovery Live Webinar 34

© CADFEM 2016

Application Areas: acoustics

ANSYS CFD 35

© CADFEM 2016

Example: Cavity Noise

© CADFEM 2016

Coupling Acoustics Pressure Spectra from Fluent >> Mechanical


• Geometry and Fluent results for car cabin noise example

10 100 1000Frequency [Hz]

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

SP

L [d

B]

Freestream Velocity = 140 km/h

Experimental data

SAS model

Sensor 123

© CADFEM 2016

Aero-Vibro-Acoustics-Coupling

• Simulation Methodology

Driver’s ear

Glass

(vibrating) Interior walls

Outer walls (rigid)

Connection between vibrating walls and rigid walls

External CFD Model Transient Flow

Vibrating Surfaces (Side Glass, Windshield)

Acoustics Model (Car Interior)

Vibroacoustics Modeling

Inflow

Compressible CFD modeling

Turbulence


© CADFEM 2016

Coupling Acoustics Pressure Spectra from Fluent >> Mechanical


• 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

© CADFEM 2016

FSI Coupling (time to frequency domain)

• transient interaction in blade rows coupled to harmonic

structural analyses


© CADFEM 2016

Improving Efficiency of Vacuum Cleaner Fans

ANSYS Colaborative Multiphysics

Source: Philipp Epple and Caslav Ilic Institute of Fluid Mechanics

Friedrich-Alexander University of Erlangen-Nürnberg, Germany, ANSYS

Solutions, 2006

Lawson model (pragmatic)


© CADFEM 2016

FSI with FEM only


© CADFEM 2016

Vibroacoustics: FEM Standing Wave


© CADFEM 2016

Vibroacoustics: FEM Propagating Wave


© CADFEM 2016

Piezo-acoustic degreasing

- 52 -

Working principle:

Ultrasonic waves are generated in an ethanol bath by a piezoelectric actuator connected

to a steel case. Tools or mechanical parts (pipes, fittings, optics,…) dived in the bath will

be subject to this varying pressure field inducing tiny micrometer scale imploding

bubbles that will help break up and dilute the polluting components.

Model:

Analysis type: full harmonic

Boundary conditions:

- symmetries

-10V on piezo element

- air impedance on liquid surface

Piezoelectric actuator:

strong coupling between DOF: Ux, Uy, Uz and Volt

Fluid:

DOF: Pressure

Structure:

DOF: Ux, Uy, Uz

FSI, Strong bidirectional

matrix coupling only at

interfaces (more efficient)

Strong bidirectional

matrix coupling only at

interfaces

ANSYS FSI, state of the art

© CADFEM 2016

Piezo-acoustic degreasing

- 53 - 53ANSYS FSI, state of the art

© CADFEM 2016

Strong coupling: timbre horloger


• Structure • Air

FSI

coupling

source: CADFEM

© CADFEM 2016

Timbre horloger: Evolution transitoire


• Evolution du spectre au cours du temps (attaque – résonnance)

© CADFEM 2016

What´s the sound of hammering piles underwater?

- 57 -

© CADFEM 2016

Offshore deep sea hammer



© CADFEM 2016

System

ANSYS CFD 59

© CADFEM 2016

Cyber Physical System

Collaborative Multiphysics 60

Robust Design Optimization RDO

Metamodels, Model Order Reduction, Co-simulation, Parametric study

product

Model Based Engineering Integrated IIoT Assets

Source: ANSYS

LIGHT &

HUMAN VISION

System Runtime

© CADFEM 2016

System Simulation & Digital Twins

Simplorer

3D Physics SimulationModel-Based Software Engineering

Model-Based Systems Engineering

ANSYS Systems & Embedded Software Capabilities for Digital Twins

RO

M

System/SW Architecture

System Safety Analysis

System Architecture

61

© CADFEM 2016

Outputs

Inputs

Industrial IoT Platform

Big Data Streaming

Big Data Analytics

Simulation Platform

Data

Digital Twin: Predictive Maintenance for Blow-Out Preventer (BOP)

GE’s Predix® Platform

62ANSYS Colaborative Multiphysics

© CADFEM 2016

Water Pumping System

PumpPipe network

Water reservoir

Users consumption

Control system

External environment

© CADFEM 2016

Temperature

stabilization at

compressor

output

0.04 m^3/s flow

control

System start-up

Example transient analysis of a compressor thermal 1D circuit with PID flow

control:

- 65 -

Thermodynamic pipe systems

© CADFEM 2016

Digital Twin: Smarter compressor

Simulation Outputs

Equipment Simulation Platform

Pump Digital Twin

PTC ThingWorx

Big Data Streaming

Big Data Analytics

InputsData

66ANSYS Colaborative Multiphysics

© CADFEM 2016

Co-Simulation/ROM with CFD Pump model

© CADFEM 2016

Component level: Solenoid Valve with ANSYS Twin Builder

- 77 -ANSYS FSI, state of the art

© CADFEM 2016

Linear ROMS Non-linear, Static Non-linear, Dynamic

Techniques

State-Space/LTI

Modal

S-Parameter

DX-ROM

Static ROM

OptiSLang

Twin Builder Dynamic ROM

Builder

Supported

Tools

Fluent, Mechanical, Icepak,

Q3D, Maxwell, HFSS, SIwave

Static ROM: Fluent

DX-ROM: Workbench/DesignXplorerAll

Limitation

Linear system only.

Specific limitation for each tool

Support enabled by tool

Static only

Extending support for new tools

requires effort

For Scalar only.

Limited input and outputs

There are three major groups of ROMs supported by Twin Builder

© CADFEM 2016

Static ROM Viewer

Visualize 3D fields of

Static ROM directly in the

Twin Builder

Visualize simulation

results like velocity and

flow rate directly on 3D

geometry

Export as Digital Twin is

also supported for Static

ROMs

Built-in Static Reduced Order Modeling (ROM) Viewer in Twin Builder

© CADFEM 2016

You can visualize the created ROM with ROM Viewer or can export it as FMU file

Change parameters and process results instantly

Export romz/FMU file

• The exported .romz file can be used in standalone ROM viewer.

• Standalone version can be launched from the following:Windows:

%ANSYS_Install_Dir%\Addins\DesignXplorer\bin\Win64\ROMViewerLauncher.bat

Linux:

$ANSYS_Install_Dir$/Addins/DesignXplorer/bin/Linux64/ROMViewerLauncher.sh

4

© CADFEM 2016

ROM Builder

81

• Thermal side inlet• Underhood with inlet ventilation and hot exhaust:

© CADFEM 2016

Dynamic ROM Builder available in Twin Builder in 2019 R1

Dynamic ROM

Support for building

Dynamic ROMs in

Twin Builder

UI for ROM building

and visualization

results

Exportable as Digital

Twin

© CADFEM 2016

Ex. 2 – nonlinear transient simulation of coil-system

• Coil System – FEM-Modell

INPUT:

Heat OUTPUT:

Core Temp

OUTPUT:

Coil Temp

© CADFEM 2016

Dynamic ROM – Technology

• The physics of the simulated problem is "learned" from the data.

• method is general:

• ‘deep learning approach’ ➔ Multilayer Neuronal Networks and backpropagation approach:

LeCun, Y., Bengio, Y., & Hinton, G. (2015). Deep learning. Nature, 521(7553), 436-444

© CADFEM 2016

Dynamic ROM Generation Prozess

© CADFEM 2016

Dynamic ROM Builder in Twin Builder

Browse to the working directory where the

training data are located


© CADFEM 2016

Discovery Live

Résultats de simulation quasi-instantannés pour dessinateurs et constructeurs

Joël Grognuz, CADFEM (Suisse) AG


© CADFEM 2016

Think of it this way…..

Discovery AIM ANSYS FlagshipDiscovery Live


© CADFEM 2016

Design

Prep

Simulate

Revise

Simulate

FinalizeWait Wait

Wait

Digital exploration

ProductIdea

DE

SIG

N

FE

M

CF

D


© CADFEM 2016

Digital exploration

• Geometry Preparation

• Meshing• Wait Time• Post

processing

DesignSimulate

Validate

Finalize

DE

SIG

N

FE

M

CF

D

Design

ProductIdea


© CADFEM 2016

ANSYS Discovery Live: Several physics - one interface – instantaneous results

footer 95

© CADFEM 2016

Fluids

ANSYS Discovery Live Webinar

• Flow geometry

• Pressure loss

• Cooling

• Free convection

• Turbulence

pressurevorticity

96

© CADFEM 2016

Demonstrator – Results – ANSYS FLUENT

© CADFEM 2016

Application Areas

ANSYS CFD 109

Complexity

Pressure drop

Pressure forces

Particle flows

(one-way)

Heat Transfer,

Cooling

Air Conditioning

Natural

Convection

Condensation,

boiling,

evaporation

Bubbly flows

Combustion,

chemical

reactions

CavitationPumps,

Fans

Turbines

Radiation

Particle flows

(two-way)

MixerErosion Sprays

Free surfaces

© CADFEM 2016

Multiphase flow

• Spray, distributions, Surface Wetting

• Cyclon filter

• Tank filling/Emptying

• Timing, Dynamics

© CADFEM 2016

Classification of Multiphase Flows: Gas-Solid Flows

• Gas–solid flow, identified as gas–solid or

gas–droplet flows, is concerned with the

motion of suspended solid or droplet in the

gas phase

• Depending on the particle number density,

these flows can be characterized as either

being dilute or dense

1=http://goo.gl/cxzTtH, 2=http://goo.gl/Ey4h6v

1

2

Dilute Dense

Fluidized Bed Reactor

© CADFEM 2016

Fundamental Definitions: Further definitions of Phase Coupling

• If the wakes and other disturbances

in the carrier phase affect the

motion of the dispersed phase, then

the flows is said to be three-way

coupled

• If in addition to dispersed

phase/carrier-phase interaction,

particle–particle collisions also

affect the multiphase motion, then

the flow is said to be four-way

coupled

Particle

Fluid

Particle

One-way coupling

Two-way coupling

Four-way coupling

Schematic diagram of coupling

© CADFEM 2016

Overview of modeling approaches

• Euler-Granular Model

• Treats continuous fluid (primary phase) as well as

dispersed solids (secondary phase) as

interpenetrating continua

• Effects of Particle-Particle interactions are

accounted based on Kinetic Theory of Granular

Flow (KTGF)

• Applicable from dilute to dense particulate flows.

Particle size distribution can also be accounted by

assigning a separate secondary phase for each

particle diameter

• Compatible with species transport, homogeneous

and heterogeneous reactionsFluidized bed simulation: Contours of

volume fraction of particles

© CADFEM 2016

Overview of modeling approaches

• Dense Discrete Phase Model (DDPM)

• Treats secondary phase solids as discrete

particles dispersed in continuous fluid

• Particle-Particle collisions are either modeled

(KTGF based approach) or explicitly resolved

(DEM based approach)

• Applicable from dilute to dense particulate flows

with wide particle size distribution

• Compatible with species transport,

homogeneous and heterogeneous reactions

• Discrete Element Method (DEM)

• Soft-sphere contact model to explicitly resolve

particle-particle collisions

• Efficiently handles dense and near packing limit

particulate flows

DDPM-DEM: Particles colored by volume fraction

DEM

© CADFEM 2016

Spray Break-up Modeling: VOF->DPM

• High-resolution VOF simulation of ligament formation and break-up

• Small spherical droplets are detected and converted to Lagrangian particle tracking

Interface Instabilities

Ligaments Droplets

VOF DPM

LagrangianTracking

VOF Tracking

Ref: “A glance at Omega-Y and VOF-DPM hybrid spray models using studies to demonstrate their

industrial applicability”, Kumar et al., ILASS-Asia 2016, 18th Annual Conference on Liquid

Atomization and Spray Systems

© CADFEM 2016

SCR: Risk assessment of urea solid deposition

• Risk factors are calculated as dimensionless quantities from 0 to 1

• Chemistry risks

• Urea crystallization

• Urea secondary reactions

• Hydrodynamic risk factors

• Low film deposition intensity

• Thick film and low heat flux

• Thick film and low velocity

• Available as a tui command

© CADFEM 2016

Particle erosion

• Particles are injected from a tube at different injection speed on a plate

specimen.

• Surface erosion was monitored as a function of time and as a function of

particle injection speed.

Plate

Inlet

Outlet

Wall

© CADFEM 2016

Workbench Integration: Quick and easy CAD => Simulate

• IC Engine (Forte) in WB

1. Cleanup

geometry using

DM or

Spaceclaim

2. Define fluid

domain

3. WB-ICE

automatically

decomposes to

required boundary

surfaces

4. WB-ICE

Generates a water-

tight surface mesh

5. Forte automatically

generates the moving volume

mesh on-the-fly, during the

simulation

© CADFEM 2016

Mesh-refinement controls for Forte automatic meshing

Solution Adaptive Temperature

Velocity

Fixed Surface

Geometry Adaptive Fixed Volume

Spark Plug

© CADFEM 2016

Spray Chamber Study

• Same fuel model as in PFI cases

• Mesh and time-step insensitivity

• Visual and quantitative comparisons

SAE2016-01-0579

U. Wisconsin ERC Experiments

EXPT EXPT EXPTEXPT

Time

Liquid penetration

CFDCFDCFDCFD

© CADFEM 2016

Application Areas – Rotating Machinery

ANSYS CFD 160

• Highly efficient time accurate

simulations with Transient Blade

Row capability (CFX)

• Several models available

• Time Transformation (TT)

• Inlet Disturbance

• Single Stage TRS

• Fourier Transformation (FT)

• Inlet Disturbance

• Single Stage TRS β

• Blade Flutter β

Surface pressure distribution (top) and monitor

point pressure (left) from an axial fan stage:

Equivalent solution with Time Transformation at

fraction of computational effort

Reference solution

without a TBR method,

requiring 180 deg model

Time Transformation

solution, requiring only

3 stator and 2 fan blades

© CADFEM 2016

Rotor dynamics

Structural elements library • mass, 3D beam, 3D pipe, shell,

3D & axisymmetric solid• 1D, 2D, 3D bearing element

Modal analysis –Campbell diagram, critical speeds

Harmonic analysis –

Response for a specified imbalance on rotor

Transient analysis –During start and stop

Fully integrated in WB and can be used for optimization & parametric study

ANSYS Multiphysics

© CADFEM 2016

Turbulence Modeling

ANSYS CFD 166

• Effects of turbulence

• Increased pressure drop

• Improved heat transfer

• Better mixing

• Noise

Laminar

Turbulent

© CADFEM 2016

Application Areas

ANSYS CFD 177

Thermal Management

• Heat transfer between fluid and solid

• Natural convection

• Prediction of heat transfer coefficients

• Radiation

• Radiation between reflecting and non-

reflecting surfaces

• Fluid participates

• Grey- and wavelength dependent

properties

• Methods: Discrete Transfer, P1,

Rossland, Monte Carlo

© CADFEM 2016

Application Areas

ANSYS CFD 180

Boiling test case based on the data in Hoyers et. al.

showing dry out at the wall

© CADFEM 2016

Reduce Total Pressure Drop and Increase Flow Uniformity

Design Iteration

Tota

l P

ressure

dro

p

Ou

tle

t ve

locity v

aria

nce

Outflow velocity

profileTotal pressure

Inflow and Outflow Geometry is fixed

~75%

reduction

~73%

reduction

© CADFEM 2016

Reduce Total Pressure Drop and Increase Flow Distribution Uniformity

Design Iteration

Tota

l P

ressure

dro

p

Outlet

mass-f

lux m

ean v

ariance

Total pressure Outflow velocity

~42%

reduction

~28%

reduction

© CADFEM 2016

Demonstrator - Results

• ANSYS FLUENT - Adjoint solver :

• Objective: drag reduction

• Auto-adjust controls

• Sensitivities post-processing

Where and how to change thebus shape to improve the drag

© CADFEM 2016

Fluent Mosaic Meshing

ANSYS CFD 190

• Today:

Still most meshs tetraeder for complex

geometries, structured hexaeder for

simple geometries

• If only…

there would be a way to combine the

adaptiveness of tet-mesh with the

efficiency of a hex-mesh.

• Today, but with Fluent Mesher:

Use patented Mosaic Meshing

Technology with the Poly-Hexcore

Mesher

© CADFEM 2016

Fluent Meshing tomorrow (2019 R3)

Simulation ist mehr als Software 191

Mosaic conformally connects the

1:8 hexcore cell size jump –

Ensure accurate results

titelmasterformat durch klicken bearbeiten ansys cfd · ansys cfd 109 complexity pressure drop...

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