A Numerical Simulation of Non-isothermal Flow and Heat Transfer of Highly-viscous Non-Newtonian Fluid through an Abrupt Contraction

Abstract

The velocity and temperature fields in non-isothermal flow of highly-viscous non-Newtonian Fluid through a planar abrupt contraction were calculated by the finite element method. It was found that the temperature rose in the slit region because of viscous heat generation and its value at x/H=80 (x: distance in the flow direction from the entrance of slit, H: half of slit thickness) was locally 30-40°C at a wall shear rate of γw=1262s-1. Since the heat conduction of fluid in the thickness direction was very small in comparison with the heat convection in the flow direction, the temperature rise near the wall increased in the slit but the temperature near the middle of slit hardly rose. The temperature profiles over the cross section perpendicular to the flow direction had a maximum near the wall and these profiles caused a difference in velocity fields between the temperature-dependent and temperature-independent viscosity flows. When the inlet temperature of the fluid was lower than the wall temperature, the maximum temperature and its position over the cross-section at x/H=80 did not change with the inlet temperature, but the velocity field did.