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Abstract : |
The extrusion how of viscoplastic fluids in shallow channels can be modeled as that occurring between two infinitely long parallel plates, i.e. the generalized plane Couette how. Commonly encountered viscoplastic fluids including concentrated suspensions exhibit apparent slip in extrusion processing. Various factors, including the roughness of the wall surface, affect wall slip behavior. and the highly viscous nature of the processed materials implies significant viscous dissipation effects. Here, we develop an analytical nonisothermal model of the extrusion of viscoplastic fluids subject to wall slip. The model accommodates different slip coefficients at the screw and barrel surfaces. Closed-form expressions for the velocity and temperature distributions, as well as the bulk temperature valid from the entrance to the exit of the extruder are presented. The conservation of energy equation is solved using the finite integral transform technique. The accuracy of the obtained solutions is established and the effects of various parameters examined. (C) 1997 Elsevier Science Ltd., |
