Fluid-Structure Interaction in STAR- CCM+ Alan Mueller CD-adapco - PowerPoint PPT Presentation

Fluid-Structure Interaction in STAR- CCM+ Alan Mueller CD-adapco

Outline Present STAR-CCM+ examples of FSI in different industries Review the challenges of FSI Examine key STAR-CCM+ technologies to enable industrial strength FSI A peek of what’s on the horizon in STAR -CCM+

Ground Transportation Fan Blade interaction in Air Abaqus STAR-CCM+

Marine Water/Air Interaction with a Flexible Structure

Off-Shore, Oil & Gas Riser Vortex Induced Vibration and Galloping

Subsea Equipment , Oil & Gas Jumper VIV with Internal VOF Flow Def.: U (x200); Field: VM stress Inlet

Aerospace Aeroelastic Flutter

Food Packaging Pouring and Gulping Courtesy Tetra Pak

BioMedical Heart Valve – Blood flow interaction with hyperelastic material

What is FSI? Ask 20 engineers “What is FSI?” and you will likely get 20 different answers There is not simply one approach valid for all FSI problems The analyst must be presented with a range of options and chose the most suitable

The Unique Challenges of FSI Simulations Protocols and formats for exchanging data – Getting data from Code A to Code B Mapping data between non-conformal meshes – Finding neighbors and interpolating Coupling methods – Algorithms for accuracy, stability, efficiency Dynamic fluid mesh evolution – Topology changes in the fluid domain Validation of FSI results 11 11

The Challenges of FSI MAPPIN G

The 3 steps of “Mapping” Searching for opposing neighbors – Most of the computer time – Robust for less than perfect meshes Interpolating source stencil data on a target point – Source and targets may be face or vertex – Strive for accuracy, conservation, boundedness Often requires integration (quadratures) – intensive extensive variables – pressure force – heat flux heat – FEA nodal loads: applicable to higher order elements.

Inconsistent Geometric Representations FEA VIEW of a WING Beam elements Kinematic Couples ? Shells(no mass,stiffness) Beam to Surface Mapping CFD VIEW of a WING

The Challenges of FSI Evolving Fluid Mesh

Simulation of Store Separation DFBI – Fluid interaction with a Rigid Body Overset Technology

Overset and Deforming Bodies Abaqus Co-simulation Overset Technology Morphing Technology Ball and Socket Stop Valve Overset + Morphing

The Challenges of FSI DATA EXCHANGE 18 18

Methods for Exchanging Data STAR-CCM+/CAE File Based Transfer: Import/Map/Export LS-Dyna� – Data exchange via files on a hard-disk Nonlinear� Crash� NX� Hypermesh� – CAE code need not be resident in memory CAD� � Meshing� &� Geometry� Morphing� – Often called “Loose Coupling” Nastran� NVH� – Exchange managed by HEEDS Analysis� SHERPA� Socket Based Transfer: Co-Simulation API – API controls exchange synchronization – Data exchanged via sockets – CAE code and STAR-CCM+ both executing in memory • STAR-CCM+ to STAR-CCM+ Co-simulation • STAR-CCM+ to 1D external Codes – GT Power, Wave, Olga, AMESim, Relap5 • STAR-CCM+ to Abaqus Co-Simulation via Abaqus API • STAR-CCM+ to External Code via STAR-CCM+ API

The Challenges of FSI Coupling Technique

Degrees of Coupling Two-way coupling for fluid-elastic equilibrium – Steady-state flow over static structure deformed by fluid loads One-way dynamic coupling – Loads only go from fluid to structure – Loads only go from structure to fluid Two-way dynamic coupling – Explicit (exchange loads once per time step) • Unstable for relatively light and/or compliant structure interacting with heavy, incompressible fluid • Interest in physics with time scales which are long compared to acoustic time scales – Implicit (exchange loads more than once per time step)

The Challenges of FSI Validations

Experimental Validation: Wedge Drop In Water 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) – Elastic Body (FE Stress)

Wedge Drop In Water Vertical acceleration Angular acceleration (rad/s 2 ) All Methods give good agreement to experiments

AeroElastic Prediction Workshop: HIRENASD 53K K node des 2.3M M cells lls

Windoff Vibration Modes : Abaqus vs Experiment f=25. 5.55 55 Hz (26.25 6.25) f=106.20 06.20 Hz f=80. 0.25 25 Hz (78.20 8.20) f=160.35 60.35 Hz (165 65.25 25)

Aerodynamic Equilibrium at different AOA Static Structure, Steady airflow at deformed shape Ma=0.8, Re=23.5x10 6 , q/E=0.48x10 -6 Lift Coefficient Wing Tip Displacement

ium Cp: AOA 2  , near wing tip Aeroel elastic stic Equil ilibr ibrium x/c STAR ST AR-CC CCM+/ +/Abaqu baqus NAS ASA A FUN3D N3D

Fluid-Elastic Instabilities in a Tube Bundle Weaver & Abd-Rabbo. A Flow Visualization Study of a Square Array of Tubes in Water Crossflow. Journal of Fluids Engineering. September 1985. Vol. 107, p. 354- 363.

Fluid-Elastic Instabilities in a Tube Bundle No other commercial, in-house, or academic code has reproduced this instability ! Vu=0.25m/s Vu=0.31m/s Vorticity

Development Trends in STAR-CCM+ Introduce and couple more physics within STAR- CCM+ Allow for co-simulation with a variety of CAE solvers Courtesy Germanischer Lloyd

Introducing DFBI Wall Contact Forces DFBI – Fluid interaction with a Rigid Body Overset Technology Contact Forces between moving rigid body with rigid walls

Introducing FEA Structural Models 3D solids, shells, and beams – Elastic Material, Non-linear Geometry – Constraints and Loads Fluid/Solid Interfaces for FSI – Solid boundary to fluid boundary – Beam to fluid boundary Dynamic with Non-Linear Geometry Thermal Stresses with CHT Flow within a vibrating pipe modeled as a beam

STAR-CCM+ Co-simulation API A library of functions and headers that can be called from an external code to enable communication with the STAR-CCM+ server – Coupling to In-house codes – Coupling to CAE vendor codes STAR-CCM+ External Code

Conclusions Many FSI challenges have been successfully addressed Demonstrated industrial “strength” examples of STAR-CCM+ The key enablers of the technology are – VOF for free surface transient flow – Overset Technology for motion and deformation – Fluid interaction with • Contacting multi-body rigid structures • Contacting deforming structures – Mapping between non-conformal meshes – Co-Simulation Application Program Interface – Parallel scalability on compute clusters

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