Moving boundary Issue

Andy

Hi Friends,

I am modeling a injector needle movement using 2D axisymetric model with the moving boundary, th eprofile is a parabolic shape. When reviewing the movement, negative volume always appear near 75% of the stroke. But if I change the cell height of the moving boundary to a much larger one (10 times of the others) together with a collapse factor 1, the movement could finish. But in this way, it will generate continuity convergence problem when I analysis. Could somebody help me with this issue?