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A Study on the Multi-Material ALE Scheme with FSI in LS-DYNA Rudolf Bötticher TMB GmbH www.rudolf-boetticher.de.

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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:

1 A Study on the Multi-Material ALE Scheme with FSI in LS-DYNA Rudolf Bötticher TMB GmbH www.rudolf-boetticher.de

2 Bonn, 10.11.2005 www.rudolf-boetticher.de 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

3 Bonn, 10.11.2005 www.rudolf-boetticher.de 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!!!

4 Bonn, 10.11.2005 www.rudolf-boetticher.de Airbag pressure

5 Bonn, 10.11.2005 www.rudolf-boetticher.de - TSSFAC=0.5 - TSSFAC def. METH=1 - Donor Cell Scheme

6 Bonn, 10.11.2005 www.rudolf-boetticher.de - TSSFAC=0.5 - TSSFAC def. METH=2 - v. Leer Scheme

7 Bonn, 10.11.2005 www.rudolf-boetticher.de Inter-ALE-material interfaces Interface tracking near FSI with three fluids Re-appearance of ALE-materials Troubles: LS-PrePost SelPar tick Fluid box

8 Bonn, 10.11.2005 www.rudolf-boetticher.de 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!

9 Bonn, 10.11.2005 www.rudolf-boetticher.de FSI-interface energy dependent on time step, which is more important than advection method Monitoring of interface advancing

10 Bonn, 10.11.2005 www.rudolf-boetticher.de User-specified penalty stiffness and leakage control important

11 Bonn, 10.11.2005 www.rudolf-boetticher.de 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

12 Bonn, 10.11.2005 www.rudolf-boetticher.de No time step dependence anymore as compared to investigation in 2004 EFG

13 Bonn, 10.11.2005 www.rudolf-boetticher.de Water Air TSSFAC=0.6 TSSFAC=0.3

14 Bonn, 10.11.2005 www.rudolf-boetticher.de DIREC=6 sp dp

15 Bonn, 10.11.2005 www.rudolf-boetticher.de 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.


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