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1© Fluent Inc. 2006. Only to be shared with Fluent Inc. clients.

Fluent for Aero, Space, and Marine

Jin Yan, Ph.D. Fluent Inc

June 12, 2006


Outline

� Overview of Current and Upcoming Product Offerings

� Fluent for Airframes� Fluent for Space� Fluent for Marine� New Core Technologies

� Conversion to and Execution on Polyhedral Meshes� Pressure-based Coupled Solver� Updates to density-based Solver� More Robust B.C.

� Conclusions


Solutions for your Enterprise

Versatile, fully-featured products at the core!

Tailored products to streamline deployment for specific purposes

Common file formats, etc. to simplify the flow of data from one group to another


FLUENT

� Heat transfer� Conduction, Convection, Radiation

� Species transport and reacting flows� Multiphase and free surface models

� Discrete Phase, VOF, Eulerian, ASM� Porous media and lumped parameter models

� Fan, heat exchangers, porous jump, porous media� Multiple reference frames, sliding mesh, mixing plane

model, and moving deforming mesh.� Acoustics� Fluid-Structure Interactions (including Aeroelasticity)

Physical Models

Solver Technology� Modern, modular, client-server, parallelized� FVM for arbitrary polyhedra; built-in adaptive meshing

� Three solver algorithms

� Coupled Density-Based (implicit or explicit)� Segregated (implicit)

� Suited for all flow regimes

� Incompressible, natural convection, subsonic, transonic, supersonic flows


� Turbulence models:

� Spalart-Allmaras

� k-ε, RNG k-ε, Realizable k-ε, RSM (LRR, SSG)� Non-equilibrium wall functions;

compressibility and transpiration effects� Two-layer/zonal models

� Low-Re models� Suite of damping function models� V2F model� k-ω (Wilcox, SST) � Reynolds Stress Model (RSM)

� Large Eddy Simulation (LES)

� Transition models (Fluent6.3)

FLUENT: Turbulence Models


Fluent: Mesh Adaption� Improve accuracy

� Refine the grid based on flow solution gradients or geometric details for higher resolution of flow details.

� Increase model efficiency� Add grid resolution only where it is needed

� Interactive, on-the-fly refinement/coarsening


Fluent - Parallel Computing

� Distributed and shared memory systems including networks of workstations

� Domain decomposition method, with grid partitioning tools and utilities for load balancing (LSF)

� Vendor-optimized message passing libraries

� UNIX, NT, Linux


Fluent for Airframes


Accurate Drag Predictions with FLUENT 6

• DLR-F4 Wing-Body Configuration

• Lockheed Martin Multi-Block Mesh

• 1.8M Hex Cells

Drag Polar, M∞

= 0.75

DPW-I


FLUENT Results on LM2 Mesh

*“Statistical Comparison of Computational Results,” presentation by M. Hemsch , slides 6, 10.

Presentation posted with the “Final Schedule and Results” on the 1st AIAA CFD Drag Prediction Workshop web site,http://aaac.larc.nasa.gov/tsab/cfdlarc/aiaa-dpw/Workshop1/Final_Schedule_and_Results.html

Red text added by Fluent Inc.

FLUENT 6,LM2 mesh, 1.8M hex’s

Expt’*Cd=0.0286

FLUENT 6 coupled solver, LM2 mesh,1.8M hex’sCd=0.0286(Interpolated from polar on previous slide)

Cd=0.0286


• DLR-F6 (DPW-II)• Wing-Body Configuration• Wing-Body-Pylon-Nacelle

• M∞

= 0.75• Lockheed Martin Multi-Block Mesh

• 1.8M Hex Cells

Accurate Drag Increments*

FLUENT Drag polars computed on coarse meshes (not on medium meshes)

20 counts

WB

WBNP

*“2 nd AIAA CFD Drag Prediction Workshop,” T. Scheidegger and G. Stuckert , Slide 5.Presentation posted with the “Final Results and Presentations” on the 2nd AIAA CFD Drag Prediction Workshop web site,http://aaac.larc.nasa.gov/tsab/cfdlarc/aiaa-dpw/Workshop2/Final_Schedule_and_Results.htm


Qualitative Features of DPW-II Case I Solution

*“2 nd AIAA CFD Drag Prediction Workshop,” T. Scheidegger and G. Stuckert , Slide 17.Presentation posted with the “Final Results and Presentations” on the 2nd AIAA CFD Drag Prediction Workshop web site,http://aaac.larc.nasa.gov/tsab/cfdlarc/aiaa-dpw/Workshop2/Final_Schedule_and_Results.htm

Only mild separation is observed in the experiment.

Many participants predicted a much larger extent of flow separation. Some prominent participants using well-established codes could not predict a consistent topology as the mesh was refined.


GA(W)-1 Airfoil


GA(W)-1 Airfoil: Results With LSQ and Polyhedral Meshes

�FLUENT 6.2� RNG k-ε model� 3rd Order MUSCL� Node-based gradients

� Higher order flux Reconstruction

�FLUENT 6.3 � RNG k-ε model� 2nd Order upwind� Cell-based least-square

gradients

� Higher order flux recons.

FLUENT 6.2 FLUENT 6.3Mesh Size Total CD (% Diff.) Total CD (% Diff.)

Experiment 0.0248 0.02482D-Airfoil 61K 0.0238 -3.91 0.0254 2.343D-Wing (Hex-Wedge) 596K 0.0235 -5.40 0.0253 2.023D-Wing (Hex-Tet) 753K 0.0279 12.463D-Wing (Hex-Poly) 392K 0.0249 -2.09


Modeling Control Surface Motion with the Moving/Deforming Mesh Capability


Virtual Blade Model (VBM)

� Individual blades are not meshed but the time-averaged aerodynamic effects of the rotating blades are modeled using momentum source terms placed inside a rotor disk fluid zone

� Source terms are computed based on the Blade Element Theory, implicitly accounting the blade twist, airfoil type, chord, and local flow incident angles

� Economical both in cell count and CPU time

� Useful for rotors and ducted fan analysis


Aerodynamics of Integration� Most applications of FLUENT to detailed design are for subsystems and

installation & integration� Difficult to develop accurate predictive models for flows in complex geometry,

especially if complex physics present

Thrust reverser efflux affects placement of engine on wing.Fluent JA134


FluiDyne Test Condition Deltas, (CFD -Test )/ Test

Data TT Core PT Core Core Bypass Corrected Total 1Nozzle

1Nozzle

Point TT Bypass PT Bypass Flow Flow Flow Thrust CD CF

2.01 1.01 1.00 -2.5% 0.86% -0.13% -0.01% -0.28% 0.05%

5.01 2.50 1.00 -5.4% 1.75% -0.39% -0.39% -0.65% -0.02%

49.01 2.50 0.86 -9.0% 1.79% -0.45% 0.03% -0.77% 0.11%

55.02 2.53 1.16 -5.2% 2.13% -0.53% -0.78% -0.86% 0.05%

1Adjusted for differences caused by Steps and Gaps in Rig Hardware - Influence approximately equal to 0.15% Cd and 0.07% CF,

Fluent ModelRig Hardware

Turbofan Mixer Nozzle AnalysisMultiMulti--species jet flow with heat transferspecies jet flow with heat transfer

Adaption used to resolve temperature gradients

Courtesy Honeywell Inc.


Engine Compartment Thermal Management

� Fire suppression system (halon dispersion)


Collection Efficiency

Contours DLRF4 wing

body configuration

M=0.4 AoA = 3deg

standard Air

Collection Efficiency for Icing Analysis


Tank Sloshing (Re: Fuel Tank Inerting)

� At t=0, container partially filled with liquid in presence of earth’s gravity

� Gravity plus surface tension (and wall adhesion) determine the initial free surface profile

� Gravity is then set to zero as the cylinder is dropped

� During a transient FLUENT simulation, the free surface gradually evolves to a new shape

� The new free surface shape is governed by surface tension and the wall adhesion angle only

Courtesy of the University of Bremen


Analysis to characterize and control aircraft vortex wakes during take-off and landing at busy airports. Fluent NL164. INTA, Spain.

Aerodynamics and Operations


Predicted CFD cold-fuel plume from ruptured left-wing of Concorde fuel tank during take-off, Courtesy Leeds University and QinetiQ

Accident Investigation with FLUENT

Columbia Investigative Report


Fluent for Space


Numerical Simulation of Mars Pathfinder Entry

Temperature Distributions and Pathlines

0.000 0.004 0.008 0.012

Axial position (m)

1E-5

1E-4

0.001

0.01

0.1

1

Mas

s F

ract

ions

CO2

N2

CO

O

N

O2

C

NO

Mass-fraction profiles along the stagnation line

“Planetary Entry Simulation,” Diego Paterna and Raffaele Savino, University of Naples, presented at the Fluent Italy UGM, October, 2000.

Thermal nonequilibrium and radiative equilibrium modeled with UDF’s

V=6.5 km/s (Peak Heat Flux Conditions)


Air Ventilation in the Space Station Cupola

Without diverter With diverter

“Analysis of Air Ventilation and Crew Comfort in the ISS Cupola,”


Payload Compartment Cooling and Spacecraft Loads

Velocity iso-surfaces showing impingement on top of payload fairing

Pressure distribution on fairing Pressure distribution on the spacecraft.


Environmental Control for X -38 “ LifeBoat ” to return Crew from Space Station

� Objective: Evaluate effectiveness of design to eliminate condensation.

� Loosely coupled to SINDA model for Thermal Protection System


Fluent for Marine


Research Vessel – Athena

Courtesy of Wesley WilsonNSWCCD, USA

� Test case for ONR Ship Wavebreaking Workshop� Full scale computation at 18 kts

X/L

Y/L

0 0.5 1 1.5

-0.2

0

0.2

0.4

0.6

Experiment

Fluent


Research Vessel – Athena

Courtesy of Wesley WilsonNSWCCD, USA

Fluent - y/b=0.86

-0.02

-0.01

0.00

0.01

0.02

0.03

-0.25 0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 2.75 3.00X/L

H/L

Measured

Fluent

Fluent - y/b=1.50

-0.02

-0.01

0.00

0.01

0.02

0.03

-0.25 0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 2.75 3.00X/L

H/L

Measured

Fluent

Wave profile along y/b = 1.5

Wave profile along y/b = 0.86


Surface-Piercing Hydrofoil

� IIHR experiments using NACA 0024 foilFr = 0.37

Re = 1.34 million

Courtesy of IIHR, U. of Iowa

FLUENT

Experiment

Rhee et al.J. Marine Science and Technology, 2005


Propeller Cavitation� MP 017 – U. of Tokyo

� Open water condition

σ

KT

and

10×

KQ

1 2 3 4

0.2

0.3

0.4

KT (Present)10×KQ (Present)KT (Data)10×KQ (Data)

Thrust breakdown at J=0.2


Computational Grid and Setup

Turbulence model SST ｋ-ωCell count 1.75 millionReynolds number 0.591×106

Courtesy of Univ. of Tokyo

Hull-Propeller Interaction using Sliding Interface


Immediate after propeller （left：experiment、right：Fluent）

Wake Velocity Contours (Self-Propelled Condition)

Hull-Propeller Interaction using Sliding Interface

Courtesy of Univ. of Tokyo


Core Technology Improvements

� Highlights from Past Year� Where We’re Going with Current Generation of

Products� Solvers� Preprocessors� Partner Products


Highlights of the Past Year

� Fluent 6.2 shipped in March of 2005� More than 300 new features (150+ enhancement requests)

� Key focus areas� Solver accuracy and transient efficiency

� MUSCL, HOFRC, BCD, NITA, coupled solver improvements, AMG…

� Non-conformal/sliding interfaces� Virtual polygon algorithm…..

� Moving & deforming mesh� Improved meshing tools, 6 DOF, generalized events handling….� IC engine submodels (spray-wall, autoignition/knock, spark ignition…..)

� Turbulence/acoustics� LES/DES SGS, BC and IC, broadband noise models, fan noise modeling….

� Reacting flows� prePDF integration, ISAT speed, NOx enhancements, fuel cell modules…

� Multiphase/VOF� Species transport and reactions, cavitation & VOF enhancements, DPM…..

� … and much more!


Immersed Boundary Method� Account for effects of thrust reverser vanes via source terms arising

from immersion of solid boundaries of vanes inside volume mesh� No need to mesh – much faster turnaround

� Implemented as UDF

Structured Base Region Unstructured Base Region


So Where Do We Go From Here?

� Extraordinary advances in speed and robustness coming in FLUENT 6.3� New Pressure-based coupled solver

� Polyhedral cells� New flux splitting schemes (AUSM+) in density-based codes for

hypersonic flows

� New Boundary conditions

� Alternate meshing strategies for extremely complex geometries in Tgrid 4.0


Faster Solutions with a Pressure-Based Coupled Solver

� Lockheed Martin mesh� 1.8M hex,multiblock structured

� Non-equilibrium wall functions

� Realizable k-ε� Ideal gas

� Solver performance comparison� Parallel, 4 nodes, -pnet, lnx86

� Single precision

� Node based reconstruction

0.05048

0.05006

0.04992

CD

0.7596

0.7538

0.7526

CL

2.2100(s)+50(t)333.5pbcs

11.8900474.0coupled implicit

3.1800142.2segregated

Time to convergence [h]

Iterations to convergence

Time per iteration [s]

Memory [GB]

DLR-F4: M=0.75, Re=3x106, a=2o


Speed-up Higher for y+=1 Meshes

� CFL3D mesh� 0.88M hex, single block� Fine mesh, y+=1� Realizable k-ε� Ideal gas

� Solver performance comparison� Parallel, 4 nodes, -pnet, lnx86� Single precision� Node based reconstruction

0.01719

0.01696

CD

0.2730

0.2691

CL

0.66160151.8pbcs

5.2700272.1coupled implicit

Time to convergence [h]

Iterations to convergence

Time per iteration [s]

Memory [GB]

ONERA M6: M=0.84, Re=12x106, a=3.06o


� Pressure-based coupled solver� Improved convergence and robustness for skewed/stretched meshes and

“stiff” problems

� Convergence rates not sensitive to mesh size

� Little need to change relaxation factors

� Ability to switch on-the-fly to fully segregated solver

Significant speed up for incompressible flow

2482101300Segregated (FLUENT 6.2)

4141360Coupled (FLUENT 6.3)

Memory (MB)CPU (min)Iterations

Solver Performance Comparison

Mesh size: 172,000 Cells


Polyhedral Cells with Pressure-Based Coupled Solver

M=0.9 inviscid flow past an F-18 (57K poly cells)2nd order numerics

• Original tet mesh had ~220k cells.

• Factor ~5 speed-up because of conversion to poly’s

• Additional factor ~5 speedup due to coupled pressure-based solver.


Density-Based Solvers Operate on Polyhedral Meshes, Too!


Improved Robustness of Density-Based Solvers for Hypersonic Flows

M∞= 8.0Viscous

Pure Roe FDS (not FLUENT)

AUSM

25o

50o

M∞= 8.0Inviscid


More Robust Boundary Conditions

� New pressure-outlet B.C. implementation in FL6.3 allows for the pressure at the outflow boundary to vary even at subsonic speed.

� The pressure at the outflow boundary is computed using a pressure splitting procedure inspired by the AUSM+

scheme of Liou

� At the exit the pressure is computed using a weighted average of left right states of the face boundary

� The weighting is a 5th-O polynomials based on the exit mach number.

� This implementation is like a poor-man NRBC


Boundary ConditionEXAMPLE: Supersonic Engine Intake Flow• The viscous boundary layer lowers the Mach number below sonic speed.

• Standard pressure implementation abruptly imposes specified exit pressure.

• New implementation provides smooth transition and hence better flow convergence.


Boundary Condition

New Pressure Implementationallow for smooth variation of pressure

when flow is subsonic

Previous constant pressure enforcementcause an abrupt change in boundary value and may require an exact specification of pressure

to avoid convergence problem

M<1 in boundary layersExample Continued


Mesh Generation Development

� Continued refinement of Tet/Hybrid methods� Emphasis on prism layers

– automation and quality

� Efficient sizing functions

� Dirty geometry handling using surface wrapping

� Focus on automated hex-dominant meshing� Hexcore and Cartesian� Boundary-fitted hex.

� BL, sizing function subtools


Handling Complex, Dirty Geometries With Surface Wrapping


Cartesian Meshing in Action


Highlights - Partnerships

� Collaboration with ABAQUS � Fluid-Structure Interaction

� CAD/PLM partnerships� FLUENT for CATIA� Deeper Pro/E integration� UGS NX/Open initiative

� Hardware partnerships� AMD, Intel� SuSE, Microsoft � Infiniband

� Complementary Solutions� Reaction Design, DEM Solutions, Optimal Solutions,

Materialise


MpCCI Enabled ANSYS-FLUENT FSI Simulation of Glider Wing

Lift (elastic) Drag (elastic)Lift (rigid) Drag (rigid)

Aerodynamic forces at 140 km/h


Mesh Deformation: Shape Optimization With Sculptor TM and

FLUENT

Courtesy Advantage CFD & Optimal Solutions. Visualization with EnSight.

� Multi-parameter optimization based on parameterized CAD models can be very time consuming (repeated generation of high quality volume meshes needed)

� New approaches, working with direct deformation of CFD meshes, show promise: (e.g. SculptorTM

working with FLUENT)


Why Fluent?� Technology

� Superior Efficiency� Pressure-based coupled solver – factor 1.5 (wall functions) to O(10) (y+=1 meshes)� Solution on polyhedral cells – factor 5 or so.

� Competitive accuracy� Powerful Tools to Adapt the Mesh� Complementary & Commercially Novel Models Available

� Immersed Boundary Method for thrust reverser vanes, etc.� Virtual Blade Model for propeller/airframe interactions

� Versatility� Preprocessing technology

� Fully-featured preprocessing solutions� Niche tools for specific applications

� Wrapper for dirty geometry comprised of parts from multiple CAD packages� Fluent For CATIA – Embedded Solution (no translation errors)

� Stability and Diversification� Self-sustaining business model

� Not reliant on any particular industry for continued investment, development� Not reliant on government contracts for small businesses.

� Market leader in CFD and in the Aerospace and Marine Industry� Enterprise-wide solutions for a global economy� Local & Dedicated Staff for Support

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