Presentation on theme: "A Study on the Multi-Material ALE Scheme with FSI in LS-DYNA Rudolf Bötticher TMB GmbH www.rudolf-boetticher.de."— Presentation transcript:
A Study on the Multi-Material ALE Scheme with FSI in LS-DYNA Rudolf Bötticher TMB GmbH
Bonn, Motivation Assess time step dependence of multi- material ALE (ELFORM=11) results for the two advections schemes with a FSI interface present. 1. Airbag - Random Error 2. Water Jet – Troubles & Monitoring 3. Duct – Leakage 4. Conclusions
Bonn, Caution: random error! Rerun input deck with *AIRBAG_ALE five times each for no- switching (UP), switching and ALE METH=1, and switching and ALE METH=2 and for two settings of the time step (TSSFAC) 32 bit single precision 5434a SMP (s_5424a_p) on dual Opteron with Windows x64 Is a LS-DYNA solver run always a deterministic function evaluation? Tested this on 9 th May 2007 with ls971_s_11220_winx64_p on the same machine: the effect has vanished!!!
Bonn, Inter-ALE-material interfaces Interface tracking near FSI with three fluids Re-appearance of ALE-materials Troubles: LS-PrePost SelPar tick Fluid box
Bonn, FSI: tweaking of *CONSTRAINED_LAGRANGE_IN_SOLID (CLIS) TSSFAC NADV METH CTYPE DIREC PFAC ILEAK Ongoing development 5434a and beyond: always use the newest version for consistency and efficiency!
Bonn, FSI-interface energy dependent on time step, which is more important than advection method Monitoring of interface advancing
Bonn, User-specified penalty stiffness and leakage control important
Bonn, Modeling Intelligent grouping of inter- ALE-material and ALE- material to Lagrangian interfaces. Individual penalty stiffness. New treatment of initial FSI- penetration on CLIS. Water Soft tissue EFG No hourglass energy! Air
Bonn, No time step dependence anymore as compared to investigation in 2004 EFG
Bonn, Water Air TSSFAC=0.6 TSSFAC=0.3
Bonn, DIREC=6 sp dp
Bonn, Conclusions The strong influence of the parameters on CLIS in conjunction with the time step on the creation of non-physical interface energy may yield low quality results. Random error with multiple CPUs! Advection scheme less important.