Fluid-Structure Int Fluid-Structure Interaction in S raction in STAR-CCM+ AR-CCM+ Alan Mueller Alan Mueller CD-adapco CD-adapco
What is FSI? What is FSI? Air Air Int Interaction with a raction with a Fle Flexible ible Structure Structure
What is FSI? What is FSI? Water/Air Int r/Air Interaction with a raction with a Structure Structure Courtesy CFD Marine Courtesy Germanischer Lloyd
What is FSI? What is FSI? Vortex Induced Vibration and Induced Vibration and Galloping Galloping
What is FSI? What is FSI? Aeroelastic Flutt elastic Flutter
What is FSI? What is FSI? Hydr Hydroplaning oplaning
Courtesy Tetra Pak What is FSI? What is FSI? Gulping Gulping
What is FSI? What is FSI? Ask 20 Ask 20 engineer engineers “ s “What is hat is FSI?” and FSI?” and you will lik u will likely ge ly get 20 t 20 dif different answ erent answers ers There There is is no not t sim simply one ly one appr approach v oach valid f lid for all FSI pr r all FSI proble oblems ms The anal e analyst must be yst must be present presented with ed with a a range of options and range of options and chose the most chose the most suitable suitable
The Uniq The Unique Challenges of FSI Simulations ue Challenges of FSI Simulations Pr Protocols and ocols and formats f rmats for e r exchanging data changing data – Getting data from Code A to Code B Mapping data Mapping data be betw tween n non-conf non-conformal ormal meshes meshes – Finding neighbors and interpolating Coupling methods Coupling methods – Algorithms for accuracy, stability, efficiency Dynamic fluid mesh Dynamic fluid mesh evolution olution – Topology changes in the fluid domain Validat lidation of FSI result on of FSI results 9
Enabling t Enabling technologies t chnologies to mee meet the challenges the challenges VOF f F for free sur r free surface trans ace transient flo ent flow Over Ov erse set meshes f t meshes for motion and def r motion and deformation rmation Fluid int Fluid interaction with eraction with – multi-body rigid structures – compliant structures Co-Simulation betw Co-Simulation between dif een different CAE codes erent CAE codes Mapping be Mapping betw tween non-conf een non-conformal meshes rmal meshes Parallel scalability on com Parallel scalability on comput ute clust e cluster
Simulation of St Simulation of Store Separation ore Separation DFBI – DFBI – Fluid int luid interaction with a raction with a Rigid Body Rigid Body Ov Over erse set T t Technology chnology
Simulation of Lif Simulation of Lifeboat Launching boat Launching VOF f F for free sur r free surface transient flo ace transient flow DFBI – Fluid int DFBI – luid interaction with a raction with a Rigid Body Rigid Body Ov Over erse set T t Technology chnology Overset grids allow simulation of launching of various devices (lifeboats, missiles etc.).
The Challenges of FSI The Challenges of FSI MAPPING MAPPING
The 3 st The 3 steps of “Mapping” eps of “Mapping” Sear Searchi ching f g for opposin r opposing neighbors neighbors – Most of the computer time Int Interpolating sour olating source st ce stencil data on a target point encil data on a target point – Source and targets may be face or vertex Ofte ten r requires i inte tegration ( (quadratures) – intensive extensive variables – pressure force – heat flux heat – FEA nodal loads: integration of intensive variables against the shape function.
Neighbor Sear Neighbor Search Im ch Imperativ perative Sear Search req ch requires little user int ires little user intervention ention The sear The search e ch excludes po cludes potential neighbors ntial neighbors based on pr based on proximity and orientation imity and orientation Critically im Critically impor portant f ant for shee r sheet me t metal par tal parts – resolve ambiguities of poor geometry – thin solid parts may be on the wrong side of the fluid surface Parallel rallel Mapping is a must! Mapping is a must! – Takes advantage of distributed memory Courtesy of Daimler
Mapping Displacement f Mapping Displacement for Lo r Low Y+ meshes w Y+ meshes C 0 continuous mapping very important for low y+ meshes Otherwise very easy for morpher to invert high aspect ratio cells in prism layer
Inconsist Inconsistent Geome nt Geometric R ric Representations presentations 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 The Challenges of FSI DATA EX EXCHANGE CHANGE 18 18
Me Methods f thods for Ex r Exchanging changing Data S Data STAR AR-CCM+/CAE -CCM+/CAE File Based T File Based Transf ansfer: Im er: Impor port/Map/Expor /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 synchronization Sock Socket Based T et Based Transf ansfer: er: Co-Simulation API 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 using Abaqus API
STAR-CCM+ : Loosely Coupled CAE Suppor AR-CCM+ : Loosely Coupled CAE Support Im Impor port CAE Mesh: CAE Mesh: import from/export to the native CAE format – Abaqus, Nastran, Ansys, STAR-CCM+ – RadTherm, es-ice Map Map & Expor & Export R Results t sults to CAE CAE – Surface Loads • Pressure, Shear Traction • Heat flux or Temperature • Heat Transfer Coeff, Ambient Temp – Volume Loads • Temperature Display mapped results on imported mesh • Heat Source Im Impor port & Map FEA R & Map FEA Results sults – Temperature Fluid Wall BC – Displacement, Eigenmodes Morpher
Heeds: W Heeds: Workflo rkflow Pr Process Contr ocess Control STAR AR-CCM+ can -CCM+ can pr provide an ide an im impor port/map/e /map/expor xport ser t service as ice as a a po powerful ul complement t com lement to HEEDS HEEDS LS ‐ Dyna Nonlinear Crash NX Hypermesh CAD Meshing & Geometry Morphing Nastran NVH Analysis SHERPA
Abaq aqus/S us/STAR-CCM+ Co-Simulation CCM+ Co-Simulation Coupling via A Coupling via Abaq aqus us Co-Simulation API of SIMULIA Co-Simulation API of SIMULIA – Manages Coupling Synchronization/Exchange/Mapping – Abaqus v6.13/STAR-CCM+ v8.04+ (implicit coupling) – Surface to Surface Mapping STAR AR-CCM+ -CCM+ A Abaq aqus us (e (explicit xplicit or or standar standard) Hydroplaning – Pressure – Shear traction Overset – Surface HTC, Tref Aba Abaqus us STAR-CCM+ AR-CCM+ – Displacement, velocity – Temperature 22 22 Ball and Socket Stop Valve
Fle Flexib ible riser le riser (L/D (L/D = = 50) in turbul 50) in turbulent cr nt crossflo ossflow. Strategy : Strat gy : Couple S Couple STAR AR-CCM+ -CCM+ to Abaq Abaqus us – Implicit Coupled on workstation STAR AR-CCM+ V -CCM+ Vortex Induced Flo Induced Flow ar around Fle ound Flexible Pipe ible Pipe Abaq aqus FEA us FEA for Fle r Flexible Pipe ible Pipe Riser dimensions: Riser dimensions: Riser cross section Riser cross section L = 3.8125 m, D = 76.25 mm T = 7.05 mm Current: Current: Vin = 1.2 m/s Re(D) = 81700 Structural ctural Material P Material Properties: operties: Young’s Modulus= 1.5 GPa; Poisson ratio = 0.42; density = 8563 kg/m 3 ;
Coupled Solution : Displacement and V Coupled Solution : Displacement and Vorticity icity z/L=0.25 L=0.25 z/ z/L= L=0.5
The Challenges of FSI The Challenges of FSI Coupling T Coupling Techniq chnique ue
Degrees of Coupling Degrees of Coupling Two-w o-way coupling f y coupling for fluid-elastic eq r fluid-elastic equilibrium uilibrium – Steady-state flow over static structure deformed by fluid loads One-w One-way dynamic coupling y dynamic coupling – Loads only go from fluid to structure – Loads only go from structure to fluid Two-w o-way dynamic coupling y 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 The Challenges of FSI Validations lidations
Experimental V Experimental Validation: W lidation: Wedge Dr dge Drop In W op In Water Com Comparison of Experiments and arison of Experiments and Models Models Peterson, W on, Wyman, and F man, and Frank: “ ank: “ Drop T Drop Tests t s to Suppor Support W Water-Im Impact and pact and Planing Boat Dynamics Theor Planing Boat Dynamics Theory ”, Dahlgren Division ”, Dahlgren Division Na Naval Sur l Surface W ace Warfare are Cent Center er, CSS/TR , CSS/TR-9 -97/25 7/25 STAR-CCM+ V AR-CCM+ VOF with dif F with different bodies erent bodies – Rigid Body (6DOF, DFBI) – Elastic Body (FV stress) – Elastic Body (Abaqus Co-Simulation) – Elastic Body (FE Stress)
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