Fluid-Structure Interface with STAR-CCM+

May 10, 2012/ Pusan DGW

CD-adapco, Seoul office, CAE1 yoochul.lee@cd-adapco.com

Introduction to this presentation

• Fluid Structure Interaction (Flow/ Thermal/ Stress) – FSI for structural engineers?

• FSI related in CD-adapco

– Only 30 min. at this event (broad & not specific) – Limited validation cases and NDA issues – Only for ABAQUS Co-simulation? – FSI domestic training course will be available – Contact us if you have FSI problem to solve !!!

Introduction to this presentation

• Contents – The challenges of FSI – DATA exchanges with FEA codes (ANSYS, NASTRAN) – ABAQUS Co-simulation interface – FSI validation cases – Meeting the Challenges of FSI

The Challenges of FSI

• Mapping data techniques

– Finding neighbors and interpolating • Protocols and formats for exchanging data

– Getting data from Code A to Code B • Coupling methods

– Algorithms for accuracy, stability • Dynamic fluid mesh evolution

– Topology changes in the fluid domain • Validation of FSI results

The Challenges of FSI : DATA EXCHANGE

• Process of DATA Exchange between codes

The Challenges of FSI : DATA EXCHANGE

• File Based Transfer: Import/Map/Export – Data exchange via files on a hard-disk – CAE code need not be resident in memory – Often called “Loose Coupling” – User responsible for exchange synch

• Socket Based Transfer: Co-Simulation API

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

DATA EXCHANGE: working with ANSYS

• Preparing DATA in ANSYS – Surface and volume used for FSI interface – The string “FSI” should be used for data mapping – SURF154(traction), SURF152(thermal) – Imported into STAR-CCM+ in *.cdb format

[CDWRITE, ALL,<filename>.cdb]

• Importing ANSYS Solution Data – By creating .lis file /output, fname, ext PRNSOL, NAME, OPT PRNSOL, TEMP PRNSOL, U, COMP /output

DATA EXCHANGE: working with ANSYS

• Preparing DATA in ANSYS – Surface and volume used for FSI interface – The string “FSI” should be used for data mapping – SURF154(traction), SURF152(thermal) – Imported into STAR-CCM+ in *.cdb format

[CDWRITE, ALL,<filename>.cdb]

• Importing ANSYS Solution Data – By creating .lis file /output, fname, ext PRNSOL, NAME, OPT PRNSOL, TEMP PRNSOL, U, COMP /output

DATA EXCHANGE: working with ANSYS

• Mapping STAR-CCM+ solution to ANSYS mesh – Using source/target proximity checks in STAR-CCM+ – Mapping tools:

each fluid boundary to ANSYS exterior surface

• Exporting to ANSYS – Via ANSYS macro scripts – “/INPUT, <filename><extension> for appropriate load step

activated – Data exported will set valued in ANSYS model e.g.) surface: D, SFE, Volume: BF

DATA EXCHANGE: working with NASTRAN

• Preparing DATA in NASTRAN – Import of shells, volumes(solids) and surface element – Through .nas or .bdf

• Importing NASTRAN Solution Data

– Form Output 2(.op2), Bulk Data file (.bdf) or (.nas)

• Exporting to NASTRAN – Mapped onto an imported NASTRAN model can be exported from

STAR-CCM+ to external files – By using

INCLUDE ‘starccm_pressure.nas’

DATA EXCHANGE: ABAQUS Co-simulation

• Coupling via Abaqus Co-Simulation API of SIMULIA – Manages Coupling Synchronization/Exchange/Mapping – Abaqus v6.12/STAR-CCM+ v7.04 (implicit coupling)

• STAR-CCM+ >> Abaqus (explicit or standard)

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

• Abaqus >> STAR-CCM+

– Displacement, velocity – Temperature

STAR-CCM+/ABAQUS Co-simulation

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Co-Simulation: STAR-CCM+ DFBI

• STAR-CCM+ Dynamic Fluid Body Interaction • Fluid loads passed to ABAQUS “on the fly” • As for the fluid, the structure is rigid

Co-Simulation: One Way Coupled Results

• Free surface/ Pressure load calculated in STAR-CCM+

Co-Simulation: Plate VIV

• Elastic plate perpendicular to air stream – 10 cm x 8 cm x 2.5mm – density and modulus such that

• 1st bending mode @ 4Hz • 1st twisting mode @ 20 Hz

• Compressible air moving at 10 m/s, Re=5e4

– K-ω turbulence model, Unsteady RANS – Rigid plate, computed Cd=2.0, Str=0.156

• Vortex shedding frequency @ 19.5 Hz • Produces very small twisting moment

Quasi-Steady Response

• All post-processing capabilities available

Experimental Validation: Wedge Wet Drop

• Comparison of Experiments and Models • Peterson, Wyman, and Frank: “Drop Tests to Support Water-Impact

and Planing Boat Dynamics Theory”, Dahlgren Division Naval Surface Warfare Center, CSS/TR-97/25

• STAR-CCM+ VOF with different bodies – Rigid Body (6DOF, DFBI) – Elastic Body (FV stress) – Elastic Body (Abaqus Co-Simulation)

Wedge Drop In Water

• Meaningful data acquired

Vertical acceleration

Angular acceleration (rad/s2)

Equivalent Stress (MPa)

Benchmark: VIV of Cylinder/Cantilevered Plate

• FSI3 Benchmark of Turek & Hron

Loads and Displacements within 10% of Benchmark Numerical Results

Wind Turbine Under Quasi-Steady Loads

• Windward Displacement can be evluated

Co-Simulation DOT Tank Impact

• Experimental impact & Numerical Analysis

DOT Tank Impact Comparisons

• Analysis results (impact force[kips])

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• CD-adapco is committed to providing state of the art tools to meet the challenges of FSI – Mapping Data Techniques – Procedures for Exchanging Data – Coupling Methods – Dynamic Fluid Mesh Evolution – Validations

• Integrating these tools into the workflow processes of our Customers

• Again, Please contact us if you need more information !!!

Meeting the Challenges of FSI