www.kostic.niu.edu/extrusion. Parametric Study. Effect of hole non-zero nitrogen pressureEffect of non-zero normal force in the outlet of the free surfaceEffect of the length of the free surface flow domain. Simulation Improvement-Refined non-uniform mesh. Fine non-uniform mesh in the corner area and in the axial flow-direction after the die exitConvective and Radiation heat transfer in the free surface.