Multiphase Modelling of Polymer (VOF/Eulerian)
 

I am trying to model the flow of a polymer under compression, using dynamic mesh and moving the rigid parallel walls (top-bottom) so that the polymer is pushed outwards to fill the domain that is initially occupied by air. The mesh is deformed with spring parameters. The two phases has been modelled by both VOF and Eulerian but both have resulted in same problem.

The main problem I see in the results is that at the polymer-air interface near the wall, air is "stack" over the wall like a thin film between the polymer and the solid wall (this observation is made looking at the phase or density countours). Therefore I can not obtain results for the polymer such as wall shear.

Other options I have used in the simulations are:

*wall adhesion (specifing angle between the phases)

*volume fraction descritization CICSAM/Geoconstruct (so makes me believe that it's not a problem of descritization)

*allowed air to slip at the wall specifing wall strain rate

*artificially increased viscosity of air to compare with the polymer one

*Immiscible fluid (in the Eulerian model)

Any suggestions please?

Volume fraction profile attached
 

(runs are transient)