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


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


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


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 …


AcuSolve Validation Manual

• Library of simulations demonstrating AcuSolve’s accuracy


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


AcuConsole Meshing


AcuFieldView

• OEM version of FieldView based on FV 14

• Client-server functionality

• Customizable graphics layout – multi-window view

• Up to 8 core parallel operation


AcuReport

• Generate reports automatically

• Write a simple Python script

• Text

• 2D Plots

• Images

• Animations


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


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]


HyperMesh / HyperView

• Pre-process by HyperMesh

• All major CAD interfaces

• Geometry cleanup / generation

• CFD volume meshing

• Post-process by HyperView

• Full CFD visualization


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


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



• Benefits

• Examples

• Future Plans

• Conclusions


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


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


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


Performance

• Parallel scalability

• Optimized domain decomposition for hybrid mpi/openmp

• Nearly perfect scalability: ~4k nodes/subdomain



• Benefits

• Examples

• Future Plans

• Conclusions


AcuSolve/MotionSolve Coupling

• Communicate using AcuSolve’s code coupling interface

• Wetted surfaces are “paired” with rigid bodies

• Loads/displacements exchanged at run time


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)



Velo

city


Streamline Animation on 200K Gallon Tank - 52’x13’


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


VG Effect on FFA-W301 @ 16o AOA (Re=3e6)

VG Location

NO VG

Increases Lift !


Tube Fin Heat Exchanger

• Compute transient thermal flow in the smallest repeatable sub-

component


Electronic Cooling

Advanced Thermal

Modeling & Analysis

(9M Elements)


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


Practical FSI Examples

• Structural displacement computed by AcuSolve

• Based on modal superposition

• Limited to linear structural displacements

• No run-time coupling


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


Rotating Machinary

• Pumps, blowers, fans

• Fast MRF – Steady

• Sliding mesh – Transient


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


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


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



• Benefits

• Examples

• Future Plans

• Conclusions


Mesh Quality Metric [14.0]

• MQM yields highly nonlinear system

• Newton iterations suffers

• Numerical stability is improved significantly through backtracking line search


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


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


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


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.


Surface Quantities

Wall Shear Stress Pressure Coefficient


Wall Functions


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


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


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


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


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


Dam Break


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


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


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


Thank You

Contour of

Mesh

Deformation

Minimize Velocity Deviation

Catalytic Converter Inlet

next generation cfd flow solver - altairresources.altair.com/altairatc.com/country/united...

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