(582a) Imposition of the Pressure-Dependent Wall Slip Condition in Mathematical Modeling of the Continuous Processing of Energetic Materials: Twin Screw Extrusion and Die Flows

Recent investigations on the development of flow instabilities during the flow and deformation of polymeric melts and concentrated suspensions (1, 2) have revealed that the slip coefficient (3), which links the slip velocity at the wall to the stress field, is itself dependent on the total normal stress (or in some situations the pressure) at the wall. In this presentation the methodology involved in the imposition of the pressure dependent slip coefficient on the coupled twin screw extrusion and die flow will be described. Typical results, focusing on the processing of energetic formulations, will be compared with corresponding modeling results using conventional flow boundary conditions.

1. H. S. Tang and D. M. Kalyon, "Time-dependent tube flow of compressible suspensions subject to pressure dependent wall slip: Ramifications on development of flow instabilities", Journal of Rheology, 52, 5, 1069-1090 (2008).

2. H. Tang and D. M. Kalyon, ?Unsteady circular tube flow of compressible polymeric liquids subject to pressure-dependent wall slip?, J. Rheology, 52, 2, 507-526 (2008).

3. D. Kalyon, ?Apparent Slip and Viscoplasticity of Concentrated Suspensions?, J. Rheology, 49, 3, 621-640 (2005).