[muskan]

Dear all,

I am trying to simulate the motion of a 3d elliptical fin. I have defined a UDF to give heave and pitch motion to the fin. My mesh is Unstructured tet with a boundary layer of hex elements.

While previewing the mesh motion, I receive an error of negative cell volume. I have tried reducing the time step as low as 0.00001s.

I have used the following settings:
1) smoothing parameters:
spring constant factor= 0.001
Convergence tolerance = 0.001
Number of iterations = 50
Elements : all
Laplace node relaxation = 1
2) Remeshing parameters: Local cell and Local face
other parameters selected according to Mesh scale info

While defining the motion I have chosen
1) rigid body motion with UDF for fin
2) Rigid body for the boundary layer with UDF
3) The fluid around the fin is set up as deforming with smoothing and re-meshing

Can anyone suggest any improvement in these settings to get rid of error?