Simulation of Carreau-Yasuda Fluid Flow with Temperature-dependent Viscosity: Non-Newtonian Lattice Boltzmann Method

In this study non-Newtonian fluid flow in two-dimensional channel with a circular obstacle has been studied using lattice Boltzmann method. The Carreau-Yasuda non-Newtonian model is used to simulate the non-Newtonian fluid behavior. The exponential model with different temperature-thinning coefficients is utilized to investigate the temperature-dependent viscosity of non-Newtonian fluid. Regarding to the local properties of the lattice Boltzmann method, the shear-dependent and temperature-dependent properties of Carreau-Yasuda non-Newtonian fluid are easily modeled with two-order accuracy. The validation of results for fluid flow and heat transfer parameters are completed, successfully. Results show a reduction in the power index of Carreau-Yasuda non- Newtonian model leads to growth of average Nusselt number, especially in high Reynolds numbers. Simulations show an increasing in the Carreau number causes to increase of wakes formed behind the cylinder. The results of drag coefficient versus temperaturethinning coefficient shows that the temperature-dependent viscosity has a significant effect on the flow field; in a way that a growth in the temperature-thinning coefficient leads to increase and decrease of drag coefficient and size of the vortices, respectively.