Next Generation CFD Flow Solver - Altairresources.altair.com/altairatc.com/country/united...
Transcript of Next Generation CFD Flow Solver - Altairresources.altair.com/altairatc.com/country/united...
Innovation Intelligence®
2015 Next Generation Computational Fluid Dynamics
Next Generation CFD Flow Solver
Farzin Shakib
VP. CFD Technology
Altair
July 7, 2015
Copyright © 2015 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved.
Outline
• AcuSolve Overview
• Benefits
• Examples
• Future Plans
• Conclusions
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Background
• AcuSolve
• Leading general purpose CFD
product suite
• AcuSolve Product Suite
• CFD Solver Engine - AcuSolve
• Pre-processing - AcuConsole
• Post-processing – AcuFieldView,
AcuTrace, AcuFwh, AcuReport,
etc.
• Global footprint with diverse
applications
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AcuSolve
• Physics:
• Incompressible & weakly compressible Navier-Stokes
• Thermal analysis
• Conjugate heat transfer
• Multi-layered thermal shell
• Enclosure radiation – View factors
• Solar radiation
• Multi-species transport equations
• Viscoelastic modeling
• Turbulence:
• Spalart-Allmaras RANS model
• Hybrid RANS/LES (DES) model & (DDES)
• K-Omega and SST 2-eqn models
• Dynamic subgrid LES models
• Time accurate transient simulation:
• Coupled with control systems
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Advanced Features
• Arbitrary Lagrangian Eulerian
• Flexible mesh motion
• Free surface
• Guide surface
• Sliding mesh
• Fluid/Structure Interactions
• Practical FSI (P-FSI)
• Direct Coupling FSI (DC-FSI)
• Rigid body & flow coupling
• Computational Aero Acoustics (CAA)
• Ffowcs-Williams Hawkings
• OptiStruct/NVH
• Export sources to acoustics codes
• and many more …
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AcuSolve Validation Manual
• Library of simulations demonstrating AcuSolve’s accuracy
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AcuConsole
• GUI-base preprocessor for AcuSolve
• Starts from CAD or MESH
• ProE, Parasolid, ACIS, Catia V5, Discrete
• HyperMesh, ICEM, Harpoon, GridGen, PointWise, …
• Generate mesh from CAD
• Automatic tet mesher
• Boundary layer
• Full problem specification
• Global parameters
• Boundary conditions, etc.
• Launch solver
• Monitor progress
• Customizable for easy deployment
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AcuConsole Meshing
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AcuFieldView
• OEM version of FieldView based on FV 14
• Client-server functionality
• Customizable graphics layout – multi-window view
• Up to 8 core parallel operation
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AcuReport
• Generate reports automatically
• Write a simple Python script
• Text
• 2D Plots
• Images
• Animations
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AcuFwh
• Ffowcs-Williams Hawkings propagation of noise to distant mics
• AcuSolve transient acoustic source passed to AcuFwh as post processor
Monopole source
-Fluctuating mass flux
-Oscillating pressure field
Dipole source
-Vortex shedding
-Trailing edge noise
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AcuTrace
• Advance particle tracer
• Laminar
• Turbulent diffusion
• Steady & Transient
• Pseudo-transient
• Parallel computation
• Auxiliary equations
• User Defined Equation
• Bi-directional coupling
• Finite mass particle [14.0]
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HyperMesh / HyperView
• Pre-process by HyperMesh
• All major CAD interfaces
• Geometry cleanup / generation
• CFD volume meshing
• Post-process by HyperView
• Full CFD visualization
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Usage Options
• AcuConsole Path
• Benefits:
• Complex geometry – complex physics
• Reliable, Fast & Accurate solution
• HyperMesh Path
• Benefits:
• Full CAD cleanup capability
• Common interface for solid/structural analysis
CAD AcuConsole AcuSolveAcuFieldView
AcuReport
CAD HyperMesh AcuSolve HyperView
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HyperStudy
• AcuSolve mesh robustness well suited for optimization
• External aerodynamics
• Morphing quick design changes
• Objective: Drag / noise / …
• Internal flows
• HVAC / exhaust / intakes / …
Flow uniformity
initial
optimum
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• AcuSolve Overview
• Benefits
• Examples
• Future Plans
• Conclusions
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AcuSolve Benefits
• A powerful general-purpose flow solver
• AcuSolve’s differentiation:
• Robustness Most problems solved on the first attempt
• Speed Coupled solver on distributed parallel machines
• Accuracy Highly accurate in space and time while
globally and locally conservative
• Easy-to-use Intuitive GUI-based pre and post processors
• Flexible Unstructured mesh for most complex industrial geometries
• Features Rich set of functionality; continuously growing
• Ideal for engineering and scientific applications
Complex physics Complex geometry/meshing
Automated solution Multi-physics
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High Fidelity Transient Solution
Flow over a Cylinder at Re=140,000 –
Isosurface of Q-Criteron colored by Velocity
Vortex street in clouds behind Robinson
Crusoe Island (same pattern as that behind the cylinder!)
Drag coefficient RMS Lift Coefficient
Experiment (CC) 1.24 - 0.18
Experiment (WA) 1.3 0.58 -
Experiment (SB) 1.35 0.5 -
AcuSolve LES 1.27 0.58 0.2
Strouhal Number
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Tolerant of Mesh Quality
• Robustness
• Forgiving regarding element quality
Reduced to 25%inflow outflow
Max. vol skew 0.9997 0.95 (remeshed, tetra in BL) 0.95 (remeshed, penta in BL)
Delta_p [Pa] 2.63 2.63 2.63
X-traction [N] 3.13e-3 3.13e-3 3.12e-3
Iterations 20 21 25
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Performance
• Parallel scalability
• Optimized domain decomposition for hybrid mpi/openmp
• Nearly perfect scalability: ~4k nodes/subdomain
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• AcuSolve Overview
• Benefits
• Examples
• Future Plans
• Conclusions
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AcuSolve/MotionSolve Coupling
• Communicate using AcuSolve’s code coupling interface
• Wetted surfaces are “paired” with rigid bodies
• Loads/displacements exchanged at run time
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Bio-mimicry: A Novel Design
• Mixing of potable water tanks
• Innovative Impeller Design
• Lilly impeller provides complete mixing of
up to 10M gallon tanks with 1/3 HP input
• Conventional mixers require 10 HP
motors and use paddle wheels
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0 2.5 5 7.5 10 12.5 15Distance from impeller
EXPERIMENTAL
CFD (3.7 millions of nodes)
CFD (6.8 millions of nodes)
CFD (8.8 millions of nodes)
Velo
city
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Streamline Animation on 200K Gallon Tank - 52’x13’
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Vortex Generation on Wings
• Requires FAST meshing
• Rapid steady state convergence
• Results indicate vortices in wake of VGs to
reduce drag and increase lift
A.25
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VG Effect on FFA-W301 @ 16o AOA (Re=3e6)
VG Location
NO VG
Increases Lift !
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Tube Fin Heat Exchanger
• Compute transient thermal flow in the smallest repeatable sub-
component
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Electronic Cooling
Advanced Thermal
Modeling & Analysis
(9M Elements)
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Active Control
• Couple with PID controller systems
• Matlab
Control Strategy Development
0.00E+00
5.00E+01
1.00E+02
1.50E+02
2.00E+02
2.50E+02
3.00E+02
3.50E+02
0 5 10 15 20 25 30 35 40 45 50 55 60
TimE (Min)
Tem
p (
C)
Element Temp Product Temp Probe Temp
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Practical FSI Examples
• Structural displacement computed by AcuSolve
• Based on modal superposition
• Limited to linear structural displacements
• No run-time coupling
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Free-Span Pipeline VIV
• Automated Simulation Tool
• Automation: CAD, mesh, input files [fluid & solid]
• Physics: Vortex Induced Vibrations, Pipe-Soil Interaction
• DC-FSI Solution: AcuSolve/RADIOSS
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Rotating Machinary
• Pumps, blowers, fans
• Fast MRF – Steady
• Sliding mesh – Transient
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Typical Workflow / Competition
• Example model took 2.5 hours to setup
Red indicates critical steps
Import CAD
• Group by Part
Name
• Separate Internal
surfs manually
• Transient
• Eddy Visc: 1e-5
• Turb: S-A
• Mesh Type: Fully
Specified
PRB • Auto Soln: Time Steps
• Time increment
• Max stagger iterations
Mesh
Motion>Rotation: Ang
Vel>Array editor
Global Mesh
Settings• Materials
OUT• Mesh Motion to
‘Rotational
Volume’
PRB
• Boundary
conditions
• Mesh motion to
interfaces
• Define interface
surfaces
• Split internal
faces
ALE
SOLVE
MSH
120 mins 5 mins 5 mins
20 mins 5 mins
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AcuConsole CAE Automation
Import CAD / HM
mesh
Define
• Solids
• Stationary Fluid
• Rotational Volume• Angular velocity
• Rotation axis
Boundary Conditions
Inlet / Outlet
Auto meshing
Auto time step
calculations
SOLVE
10 minutes
• Process intelligence
• Fast setup: 4 steps
• Auto meshing
• Auto solving strategy
• Time steps calculation
4
2
3
1
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Simulation Based Design
Evaporator Module
Performance Validation
Module System Master Assembly
Sealed System Module Set
Validation of Thermal
Requirements
Module System
Validation of Supply
Chain Requirements
Water Heater
Performance Validation
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• AcuSolve Overview
• Benefits
• Examples
• Future Plans
• Conclusions
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Mesh Quality Metric [14.0]
• MQM yields highly nonlinear system
• Newton iterations suffers
• Numerical stability is improved significantly through backtracking line search
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Improved Interpolated Mesh Motion (MMI) [14.0]
Reduced surface mesh
Auxiliary tetrahedral
mesh
Nodal Disp. BCs
Mesher
Original surface mesh
Decimation
Mesh projection
3D Version
• Large cases with moderate deformation
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K-Omega & SST Turbulence Models [14.0]
• Improved accuracy on highly separated flows
• Direct access to turbulent kinetic energy
• Pre-requisite for turbulent transition models
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Validation: Airfoil
• Nakayama Model A airfoil
• Subsonic “Model-A” airfoil
• Angle of attack = 0.0
• Re= 1.2 million
• M = 0.088
Nakayama, A., "Characteristics of the Flow
around Conventional and Supercritical Airfoils," J.
Fluid Mech. (1985), Vol. 160, pp. 155-179
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Validation: Driver Experiment
• Separated boundary layer
• Subsonic flow through an axisymmetric
diffuser
• Re= 2.0 million
• M = 0.088
"Reynolds Shear Stress Measurements in a Separated
Boundary Layer Flow," AIAA Paper 91-1787, from the
AIAA 22nd Fluid Dynamics, Plasma Dynamics, and
Lasers Conference, June 1991, Honolulu, HI.
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Surface Quantities
Wall Shear Stress Pressure Coefficient
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Wall Functions
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Design Optimization [Post 14.0]
• Built-in Design Optimization in AcuSolve
• Steady State
• Cyclic Transient
• Example
Minimize objective(u,y)
subject to constraints(u,y)
Flow solution (Velocity, Pressure, …)
Design variables (Morphed shapes, …)
objective: drag
constraints: volume ≥ initial_volume
Navier-Stokes
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Catalytic Converter
• Compressible flow - Ideal Gas
• Minimize velocity deviation
• 16 morphed shapes
max|vel|=68.9m/s max|vel|=56.3m/s
∆p=10820
∆p=7825
Velocity Standard Deviation ~33% reduction
3x faster than
optimization with
HyperStudy
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HVAC
• Minimize exist velocity deviation
• 12 Morphed shapes
• Strategy
• Sample every step
• Optimize every 5th step
• No approximate sampling
Normal velocity at
evaporator inlet
Deformations
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Development Plans
• Short term
• Steady and cyclic flows
• Shape & parameter optimization
• Morphing via HyperMorph
• Direct method
• Long term
• Free shape optimization
• Control point shape
• Adjoint method
• Multi-domain optimizationTransient detached eddy simulation
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Volume-of-Fluid (VOF) [Post 14.0]
• Conservation
• Mass, volume fraction, momentum, …
• Interface
• Interface restoration
• Accurate surface tension
• Unstructured mesh
• Avoid curvature computation
• Stable & fully parallel
• No CFL limitation for stability
• Large density variation
• No spurious side effects
Water & Air
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Dam Break
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Development Plans
• Short term
• Unified input structure
• Cahn-Hilliard equations
• Two-phase VOF
• Long term
• Multi-phase VOF
• Disperse phase
• Mixture model
• Chemical reaction (with partner)
• Longer term
• Euler-Euler
• Cavitation
Cahn-Hilliard
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AcuConsole [Post 14.0]
• HyperMesh Unity - UI/UX
• Modern interface
• Improved user experience
• Power of HyperMesh
• New ribbon layout
• Workflow improvement
• All AcuSolve commands
• Attribute driven setup
• Volumes: meshing, material models, body forces, etc. are independent
• Surfaces: meshing, boundary conditions, radiation, output, etc., are independent
• New report generation
• Customization
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Conclusions
• AcuSolve is a powerful general purpose CFD code
• AcuSolve differentiation
• Scalability Easy to Use
• Quality Rich functionality
• Robustness Well validated
• Ideal for engineering and scientific applications
• Complex physics Complex geometry/meshing
• Automated solution Multi-physics
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Thank You
Contour of
Mesh
Deformation
Minimize Velocity Deviation
Catalytic Converter Inlet