Polymer flows dominated by high heat generation and low heat transfer

This paper aims to review recent studies of the flow of non Newtonian (temperature and shear rate dependent) viscous fluids and to relate them to commonly encountered difficulties in polymer processing. The flows considered take place in narrow channels or pipes, and are dominated by viscous forces. Heat generation and temperature variations are taken to be the most significant aspects. A dimensionless formulation of the energy and stress equations is employed, thus bringing out the role of Graetz, Nahme‐Griffith and Brinkman numbers. These latter are introduced as ratios of temperature differences. Special consideration is given to the question of the stability of such flows.