dynamic meshing
 

hello i m using dynamic mesh model for analysis of i c engine my problem is at the time of mesh preview as soon as the piston is coming to the tdc at the end of compression stroke its creating negative cell volume(because at the same time valve opening event also starts and my clearance between the tdc and cyl head is less than 1 mm and cyl head is flat)is creating because of the geometry?and at layering is also not taking place.i m not getting where to play. if anybody is having material related to this problem plz forward me.plz do the needful thanks in advance pritam