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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
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© 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
7ANSYS FSI, state of the art
© 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
ANSYS FSI, state of the art 12
© 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
ANSYS FSI, state of the art 19
© 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
20ANSYS FSI, state of the art
© CADFEM 2016
Mesh Deformation and Fluid-Structure-Interaction
• Eulerian explicit (FEM)
Aquaplaning
© CADFEM 2016
…on the rocks!
ANSYS FSI, state of the art 22
© 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.
23ANSYS FSI, state of the art
© 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?
25ANSYS FSI, state of the art
© 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
33ANSYS FSI, state of the art
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© 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
ANSYS FSI, state of the art 39
• 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
40ANSYS FSI, state of the art
© CADFEM 2016
Coupling Acoustics Pressure Spectra from Fluent >> Mechanical
ANSYS FSI, state of the art 41
• 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
42ANSYS FSI, state of the art
© 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)
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© CADFEM 2016
FSI with FEM only
ANSYS FSI, state of the art 49
© CADFEM 2016
Vibroacoustics: FEM Standing Wave
50ANSYS FSI, state of the art
© CADFEM 2016
Vibroacoustics: FEM Propagating Wave
51ANSYS FSI, state of the art
© 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
ANSYS FSI, state of the art 55
• Structure • Air
FSI
coupling
source: CADFEM
© CADFEM 2016
Timbre horloger: Evolution transitoire
ANSYS FSI, state of the art 56
• 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
ANSYS FSI, state of the art 58
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© 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
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© CADFEM 2016
Discovery Live
Résultats de simulation quasi-instantannés pour dessinateurs et constructeurs
Joël Grognuz, CADFEM (Suisse) AG
ANSYS Discovery Live Webinar 87
© CADFEM 2016
Think of it this way…..
Discovery AIM ANSYS FlagshipDiscovery Live
ANSYS Discovery Live Webinar 88
© CADFEM 2016
Design
Prep
Simulate
Revise
Simulate
FinalizeWait Wait
Wait
Digital exploration
ProductIdea
DE
SIG
N
FE
M
CF
D
ANSYS Discovery Live Webinar 90
© CADFEM 2016
Digital exploration
• Geometry Preparation
• Meshing• Wait Time• Post
processing
DesignSimulate
Validate
Finalize
DE
SIG
N
FE
M
CF
D
Design
ProductIdea
ANSYS Discovery Live Webinar 91
© 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
Virtual Wind Tunnel Application: Discovery Live
footer 99
© CADFEM 2016
Virtual Wind Tunnel Application: Discovery Live
footer 100
© 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
Fluidised bed including mass transfer from powder to fluid
ANSYS CFD 124
© 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
Visualization of Forte results
• Including automatic reporting through WB-ICE
© 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
Application Areas – Rotating Machinery
ANSYS CFD 165
• Shear stress and velocity streamlines:
© 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 179
• Room Temperature
© 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