1. 26-27 September 2005 Colloque GDR Intéraction Fluide-Structure, Sophia Antipolis 1 Fluid-Structure Interaction Modelling with Europlexus Fast Dynamics Software S. Potapov EDF R&D – Analyses in Mechanics and Acoustics Colloque GDR Interaction Fluide-Structure Sophia Antipolis, 26-27 September 2005

2. 26-27 September 2005 Colloque GDR Intéraction Fluide-Structure, Sophia Antipolis 2 Outline Industrial context Numerical tool Incompatible FS interface Validation example Conclusion

3. 26-27 September 2005 Colloque GDR Intéraction Fluide-Structure, Sophia Antipolis 3 Loss Of Coolant Accident (LOCA) Main Primary Circuit of PWR Reactor vessel Pipeline model Mixed pipeline / 3D model 1D/3D Fluid-Structure link PP GV break anti-whipping devices

4. 26-27 September 2005 Colloque GDR Intéraction Fluide-Structure, Sophia Antipolis 4 * transient phenomena (wave propagation) * fluids, structures and their interaction (FSI) * Lagrangian, Eulerian and ALE formulations * geometric and material non-linearities * 1D, 2D, and 3D modelling (1D/3D connexions) * finite element formulation + transport terms * explicit time integration (initiated by CEA in 1978, and developed jointly by CEA, JRC, EDF, SAMTECH since 2000) Domains of analysis: Applications: Main characteristics: 1) pipe circuits 2) hydrodynamics 3) explosions 4) impacts 5) robotics - nuclear reactors - chemical plants - off-shore structures - submerged pipelines - safety valves Principal models available for the FSI analysis: gas (perfect) two-phase water - homogeneous equilibrated - steam tables pressure losses (distributed) multi-pipe links: pump, break, local pressure losses pipes: * 1D elements : rigid and flexible walls * 3D fluid and structure elements * Compressible fluid materials: tetrahedron, cube beam, plate, shell 1D-3D F and S connexions EUROPLEXUS fast dynamics code

5. 26-27 September 2005 Colloque GDR Intéraction Fluide-Structure, Sophia Antipolis 5 3D Fluid-Structure coupling in EUROPLEXUS n F r -r S equality of reactions n F vSvS S vFvF compatibility condition Structure Fluid compatible meshes C v = b M ü = F ext - F int m n ü n = f ext - f int + r n n n Dynamic equilibrium over the whole domain: Kinematic links: Equilibrium for the FS interface d.o.f.: r n = C T Reactions at the FS interface: v F.n = v S.n For inviscid fluid: Structure Fluid Hierarchical type interface Incompatible FS interfaces:

6. 26-27 September 2005 Colloque GDR Intéraction Fluide-Structure, Sophia Antipolis 6 Non-matching coupling conditions node

7. 26-27 September 2005 Colloque GDR Intéraction Fluide-Structure, Sophia Antipolis 7 FSI simulation of LOCA accident in HDR HeissDampfReaktor (KFA/ISR, Germany, 1980) Blowdown nozzle Core barrel Downcomer Mass ring Pressure vessel Lower plenum Membrane Blowdown nozzle: L = 1.37 m A = 0.0314 m 2 Core barrel: H = 7.57 m R = 1.32 m t = 0.023 m Mass ring: M = 13500 kg (Superheated Steam Reactor) Experiment V32 Initial conditions: break water P = 11 MPa T = 300 °C

8. 26-27 September 2005 Colloque GDR Intéraction Fluide-Structure, Sophia Antipolis 8 HDR model with EUROPLEXUS Coarse mesh Fine mesh Refinment procedure Fluid mesh Incompatible interface Structure mesh Nb. of elements : Fluid : 35854 Fluid : 34204 Structure: 2080 Structure: 1148

9. 26-27 September 2005 Colloque GDR Intéraction Fluide-Structure, Sophia Antipolis 9 Evolution of pressure compatible mesh incompatible mesh P x 0.1 (MPa)

10. 26-27 September 2005 Colloque GDR Intéraction Fluide-Structure, Sophia Antipolis 10 Time histories of pressure and displacements

11. 26-27 September 2005 Colloque GDR Intéraction Fluide-Structure, Sophia Antipolis 11 Calculations with and without FSI

12. 26-27 September 2005 Colloque GDR Intéraction Fluide-Structure, Sophia Antipolis 12 Time performance Matching mesh: Fluid: 35854 FE Fluid: 34204 FE Structure: 2080 FE Structure: 1148 FE Non-matching mesh: on Compaq  25 4

13. 26-27 September 2005 Colloque GDR Intéraction Fluide-Structure, Sophia Antipolis 13 The use of the new non-matching FS interface algorithm allows realistic prediction of different physical phenomena characterising the LOCA situation This algorithm allows optimising physical modelling and mesh generation for the fluid and structure domains The CPU time is drastically reduced Conclusion