Heat and Flow Properties of a Temperature Dependent Viscoplastic Fluid Including Viscous Dissipation

The present study concerns the numerical analysis using the finite volume method, of laminar forced convection flow of a viscoplastic fluid. The flow takes place in a circular pipe maintained at uniform wall temperature. The fluid consists of the sloe fruit juice with low pulp and pectin contents which obeys the rheological model of Bingham. The Nusselt number and the friction factor when both viscous dissipation and variability of the viscosity upon temperature for heating and cooling cases are taken into account are calculated and compared to those obtained for an isothermal flow when viscous dissipation is neglected. The results show that neglecting both viscous dissipation and the temperature dependency of viscosity leads to underestimate heat transfer and pressure drop.