Axisymetric modeling of free-surface for polymer

hayden

Hi, I have recently started using Fidap and am tring to model the free surface of a polymer melt which is necking down due to an applied tensile force.

My boundary conditions for the polymer are a presrcibed exit velocity and exit normal stress and a prescribed inlet diameter. All other unknowns can be found due to conservation of mass and momentum. However I am having problems and it does not quite converge. The results are not physically correct as the polymer does not neck down (ie decrease diameter) even though it accelerates (due to the applied force). Therefore mass is not conserved.

Does anyone have any ideas about what I might be doing wrong. Any help would be greatly appriciated.

Hayden.