ENTROPY GENERATION FOR A NON-NEWTONIAN SHEAR THINNING FLUID WITH VISCOUS HEATING EFFECTS

摘要

This paper reports the entropy generation of a two-dimensional, non-isothermal, steady, hydrodynamically and thermally fully-developed flow of an incompressible, non-Newtonian shear thinning fluid between two infinite parallel plates. The inelastic fluid is modeled by a two parameter Carreau constitutive equation with an exponential temperature dependence of viscosity. Temperature dependence of the fluid is modeled through Arrhenius law. Momentum and energy balance equations, which govern the flow, are coupled, and this nonlinear boundary value problem is solved numerically using a Pseudospectral method based on the Chebyshev polynomials. The effect of various flow controlling parameters on velocity, temperature and entropy generation is analyzed. The results indicated that Brinkman number and activation energy have opposite effects on entropy generation due to heat transfer. In contrast to the power-law index, an increase in the material time constant results in a decrease in the Bejan Number.