A. Lawal et Dm. Kalyon, NONISOTHERMAL MODEL OF SINGLE-SCREW EXTRUSION OF GENERALIZED NEWTONIAN FLUIDS, Numerical heat transfer. Part A, Applications, 26(1), 1994, pp. 103-121
A nonisothermal model of the single - extrusion Processing of generali
zed Newtonian fluids is presented. Various temperature dependent forms
of a generalized Newtonian fluid constitutive equation representing t
he Herschel-Bulkley fluid and its simplifications, including Bingham p
lastic, power law of Ostwald-de Waele, and Newtonian fluids, are appli
cable. The model includes the generally ignored transverse convection
terms of the equation of energy. The importance of keeping the transve
rse convection terms in the analysis is demonstrated by applying the m
odel and comparing findings to experimental results involving the tran
sverse flow temperature distributions in single screw extruders, avail
able in the literature. The numerical instabilities, arising principal
ly from the convection terms, generally encountered in high-Peclet-num
ber extrusion flows, could be eliminated by the use of the streamline
upwind / Petrov-Galerkin formulation. The model is sufficiently genera
l to accommodate Navier's wall slip at the wall boundary condition com
monly encountered during the processing of gels and concentrated suspe
nsions.