Dynamic mesh for huge deformation

[Farah]

Hi
i am running dynamic mesh using UDF on Fluent and my simulation crash and this is how mesh preview looks like. as you can see it gets jagged in some regions. i have been trying different remeshing and smoothing and this is what i got at best (18% run then crash with negative cell volume) . if you could hav any thhoughts on how to handle extrenly large deformation in complex gemetry i appreciate it.  mesh size: 2mm tetrahedral (i also tried 0.5, 1, 2, 4 and in each scenario polyhedra but failed and so far this case is the longest-run i have made), time-step: 0.001, smoothing: spring/laplace/boundary layer with diffusion parameter=0.5, Generalized Boundary Distance Method activated, (i also tried diffusion-based) , remeshing: method's based only change the size remeshing interval from 5 (default) to 1., max face skewness limit= 0.7) 

[Petros]

Hi, can you provide some pictures of the mesh? Remeshing with polyhedral is a beta feaure and not guaranteed to work properly, so better stay with tetrahedral. The chosen timestep should ensure that the resulting motion does not cross more than one cell per step (preferably set it to half the value of min cell size / velocity).