Negative cell volume problem in-cylinder
 

I'm doing a dynamic mesh simulation with in-cylinder cold flow (fluent tutorial). My mesh is OK when imported into fluent. However, I got this error after several itterations in mesh motion:



Updating mesh to time 1.98750e-02 (step = 00477) (crank-angle = 598.50)...

WARNING: non-positive volumes exist.

Dynamic Mesh Statistics:
Minimum Volume =-9.18062e-010
Maximum Volume =2.09744e-006
Maximum Cell Skew =5.96430e-001 (cell zone 7)
Warning: negative cell volume detected!
Error: Update dynamic mesh failed. Negative cell volume detected.
Error Object: ()


How can I fix this?

thank in advance