Effect of Fluid Inertia on the Liquid Flow Phenomena through a Two-Step Tapered Backward Channel

Abstract

The computational model is developed through the computational fluid dynamics (CFD) package COMSOL Multiphysics and adopts the least square residual approach with the combination of the Galerkin finite element technique. The scheme is applied to the steady state solution of the 2nd order momentum equation in Cartesian coordinates form to satisfy the continuity equations, and completes two-parameter velocity and pressure separately. Due to the least square residual approach, an extra parameter, vorticity, is assumed to decrease the 2nd order diffusion term in the momentum equation into the system of first-order governing equations. Two cases of fluid flow features are examined as Newtonian, shear thinning (n=0.95 and 0.90), and shear thickening (n=1.1 and 1.2), with and without the availability of Porous material. The flow patterns are visualized into the streamline patterns of velocity and pressure with the differences of non–dimensional Reynolds number. Also, various plots are developed for the recirculation flow rate and vortex length with the newly established empirical equations for both fluids. The small eddies are developed into the left (primary) and right (secondary) silent corners of the cavity at lower Reynolds numbers, and as the Reynolds number increases, the primary eddy is enlarged in Newtonian fluids, very slowly enhanced in the shear thickening fluids, and greatly grows the primary vortex in the shear thinning fluids. Conversely, all eddies vanish to fill the Porous material. The finite element results are compared with the other predicted results, and a good approximation is achieved on the basis of available literature.

Keywords: Fluid Inertia, Liquid Flow Phenomena, Curved Converging Channel