Power-law fluid flow in driven enclosures with undulation using MRT-lattice Boltzmann method

摘要

In this article, the flow of non-Newtonian fluid (which is represented by the power-law model) in two-dimensional (2D) driven enclosures is studied. The enclosure consists of regular, rectangular shaped undulations on the bottom wall. Multiple-Relaxation time (MRT) collision model for the lattice Boltzmann equation method (LBM) is employed. First, numerical validation is performed by comparing the MRT-LBM results of power-law fluid flow inside the wall-driven square enclosure (no undulation) and flow inside diagonally flipped L-shaped enclosure with the literature. The strain rate profiles for square enclosure without undulations are compared using various equations available for strain rate calculation in the LBM literature. Further, the effect of different values of the non hydrodynamic relaxation parameters on the flow is examined. Then, for the undulated enclosures, flow features and eddy dynamics are analyzed and discussed for the variations in the power-law index, n, to represent shear-thinning and shear thickening fluids. The effects of various parameters such as Reynolds numbers, wall undulation heights and wavelength of undulations on the power-law fluid flow are analyzed. Also, the variation of viscosity with spatial location for steady-state flow and total kinetic energy within the computational domain are presented for various values of power-law index. (C) 2017 Elsevier Ltd. All rights reserved.