FIDAP-simulation with high viscotities

Wolfgang Korte

I use FIDAP to simulate a flow of molten plastic through a nozzle. Typically the viscosities of the plastic is very high (approx. 1000 to 10000 Pa s) and the velocities are very low (approx. 0.010 m/s), high pressure losses have to be expected (approx. 100 bar to 500 bar). I have severe problems to get convergence of the solution and if convergence is achieved the solution does not appear physically meaningful. I used the segredated solver as well as a coupled solver. For both solvers the solution diverged after more or less iterations. I have already tried several methods of stabilization and convergence acceleration etc. (e.g. INCREMENTAL, RELAXATION, UPWINDING). Also I have increased the viscosity incrementally via RESTART-Runs to get an initial solution for the subsequent iterations. Nothing of all helped so solve the problem. Does anybody has an idea.