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Mee eeting ing t the C e Chal allenges enges

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Fluid-Str tructu ture I Interacti tion

Alan Mueller, Chief Technology Officer

Air Interac action wit ith a a Flexible S Structure

What at is F is FSI SI?

Water/Air I Interac actio ion with a a Structure

What at is F is FSI SI?

Vortex Induced V Vib ibrat ation an and Gal allo loping

What at is F is FSI SI?

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Aeroelas astic F Flutter

What at is F is FSI SI?

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Hyd Hydroplan aning

What at is F is FSI SI?

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Gulp ulping ng

What at is F is FSI SI?

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Ask 20 en engi gineers “What is FSI SI?” and d you will likely ge get 2 20 di different answe wers There is not simply one ap approac ach v valid alid for al all FSI problems The an anal alyst must be presented wit ith a a ran ange of options an and chose the most suitab able

What at is F is FSI SI?

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Map Mappin ing d dat ata a techniques

– Finding neighbors and interpolating

Protocols a and format ats f for exchan anging data

– Getting data from Code A to Code B

Coupling methods

– Algorithms for accuracy, stability

Dynam amic ic fluid mesh evolu lutio ion

– Topology changes in the fluid domain

Valid alidat ation of F FSI r result lts

The The C Cha hallenges of

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Th The Ch Challenges o

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MAPPI APPING NG

Sea Searching g for opposing n nei eighbors Interpola latin ing source s stencil dat ata a on a a tar arget point

– Source and targets may be face or vertex

Often en requires i integr egration (quadratures es)

– intensive extensive variables

• pressure

force

• heat flux

heat

– FEA nodal loads: integration of intensive variables against the shape function.

The The 3 3 steps of

• f “Ma

Mapping”

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Sear arch r requir ires l lit ittle user in intervention The sear arch exclu ludes potentia ial l neig ighbors bas ased o

• n p

proximit ity an and

• rientatio

ion Critic ically y importan ant for s sheet metal al parts

– resolve ambiguities of poor geometry – thin solid parts may be on the wrong side of the fluid surface

Par aral alle lel Map Mappin ing is is a a must!

– Takes advantage of distributed memory

So Source N Neig ighbor Se Sear arch I Impe perative

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Co Co-Simulation

• n V

Vehi hicle The Thermal Ma Management

Mappi apping D Disp isplac acement in in Low w Y+ Pr Prism M Mesh shes

14 C0 continuous mapping very important for low y+ meshes Otherwise very easy for morpher to invert high aspect ratio cells in prism layer

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DATA E A EXCH CHANG ANGE

File e Based ed Transfer er: Imp mport/Map/Export

– Data exchange via files on a hard-disk – CAE codes need not be resident in memory – Often called “Loose Coupling” – User responsible for exchange synch

Socket Based ed Transfer er: Co-Sim imulat atio ion API

– CAE code and STAR-CCM+ in memory – Data exchanged via sockets – API controls exchange synchronization

Metho hods f for E Excha hanging D Data

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Coup upling ng via Abaqus us Co-Sim imulat atio ion API of SIMULIA

– Manages Coupling Synchronization/Exchange/Mapping – Abaqus v6.12/STAR-CCM+ v7.04 (implicit coupling)

STA TAR-CCM CCM+ Abaq aqus (explic icit it o

• r stan

andar ard)

– Initial geometry – Pressure(relative or absolute pressure) – Shear traction – Surface heat flux

Ab Abaqus s STA TAR-CCM CCM+

– Displacement, velocity – Temperature

Ab Abaqu qus/STAR-CCM CM+ C Co-Sim Simulat atio ion

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Ab Abaqu qus/STAR-CCM CM+ C Co-Sim Simulat atio ion I Interfac ace

18 Hit the Step or Run button to commence the co-simulation

The The C Cha hallenges of

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Co Coup uplin ing T g Tech echniq nique

Tw Two-way y couplin ling f for ae aeroelas astic or hydroela lastic ic equilib ibriu ium On One way y stat atic ic coupling for thermal stresses

– structural temperature computed by CFD CHT

On One way y dyn ynamic c couplin ing

– Loads only go from fluid to structure – Loads only go from structure to fluid

Two way dynam amic ic c coupling

– explicit (exchange once per time step) – or implicit (multiple exchange per time step)

Degre rees o

• f Coupli

ling

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Dyn ynami mic Mesh esh Ev Evolu luti tion

The The C Cha hallenges of

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Completely def define a go good quality fluid d mes mesh

– Using as little user intervention as possible

Op Options w within STAR-CCM CCM+

– Rigid body motion, sliding interfaces – Morphing – User Defined Motion

Over erset Mes esh

Dyn ynamic Me Mesh E h Evol

• lution

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Overs rset Me Mesh Mo h Motion a and F Flu luid F Flo low : : Stop V Valv lve

Th The Ch Challenges o

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Val alida idatio ions

AeroElast astic ic Predic dictio ion Work rksho hop: H : HIRENASD

2.3M cells 53K nodes

Stat atic ic Structure, Steady air airflow at at deformed shap ape Ma=0.8, Re=23.5x106, q/E=0.48x10-6

Aerodynamic amic E Equil ilib ibriu ium m at d different A AOA

Wing Tip Displacement Lift Coefficient

Cp Cp: AO AOA 2°

FUN3D STAR-CCM+/Abaqus

Cp Cp: AOA AOA 2°, S Stat atio ion 7

x/c

STAR-CCM+/Abaqus NASA FUN3D

Wi Wind nd-off Vibrat atio ion M Modes : s : Abaqus s vs vs Experi riment

f=25.55 Hz (26.25) f=80.25 Hz (78.20) f=106.20 Hz f=160.35 Hz (165.25)

AeroElast astic ic Predic dictio ion Work rksho hop: : Forced V d Vibrat atio ion o

• f

2nd

nd Flap Be

ap Bending M Mode de

Magnitude Wing Tip Response

• f Cp

Phase

Fluid id-Elast astic ic I Inst stab abil ilit ities i s in a Tube B Bundle Weaver & & Ab Abd-Rabbo bbo, “A “A Flow Visual aliz izat atio ion S Study dy o

• f a Squar

are A Array o

• f

Tubes i in Water r Cr Crossflow”

31 HydroDynamic Damping: Simulation vs Measured Vibration RMS vs Inlet Velocity: Simulation vs Measured Tube Bundle Vorticity

Co Co-Simu Simulat ation D DOT T Tank I Impact

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Experimental Test Impact

DOT T Tan ank I Impac pact Sim Simulations

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Von Mises Stress (Abaqus Explicit) STAR-CCM+ Pressure

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DOT Tank Impact Comparisons

Map Mappin ing D Dat ata a Techniques Procedu edures es f for Exchangi ging Data Coupling Methods Dyn ynamic Flu luid id Me Mesh Evolution Valid alidat ations

The The C Cha hallenges of

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Than ank Y You For Y Your A Attention & & Enjo joy

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