mesh motion setup in enginefoam
 

Hi everyone, I am a new user in 1.6-ext. It is so fun to find there is dynamic engine mesh type in this version. But when I run the tut case of 1.6-ext for enginefoam, it crashes after running several time. The error is like below:
--> FOAM FATAL ERROR:
negative cell volume. Error in mesh motion before topological change.

From function bool layerAdditionRemoval::changeTopology() const
in file polyMeshModifiers/layerAdditionRemoval/layerAdditionRemoval.C at line 293.

FOAM aborting

I guess the reason is because the mesh motion is too fast, but I don't know how to set correctly and tried several times it always messed up.The mesh size is 6.386e-3(moving direction).Actually I didn't change parameters set in tut case originally, but only engineGeometry to use dynamic mesh.
Thanks