Simulating the Flow of a Thixotropic Fluid above a Fixed Plate at Arbitrary Reynolds Numbers

Abstract

In the present work, laminar flow of an incompressible thixotropic fluid is investigated numerically above a fixed semi-infinite plate. Assuming that the fluid of interest obeys Harris' thixotropic rheological model, vorticity/stream function formulation will be used to reduce equations of motion. The equations so obtained are then solved numerically using the finite difference technique. It is shown that for the Harris model to represent true thixotropic fluids (in a Lagrangian sense) the thixotropic parameter appearing in this fluid model should be negative. Numerical results obtained at a typical location (say, in the middle of the plate) show that for the viscosity to decrease by an increase in the thixotropic parameter of Harris model, this fluid property should be negative. Interestingly, an increase in the velocity gradient near the wall combined with a decrease in the viscosity of the fluid is predicted to give rise to an increase in the wall shear stress regardless of the fluid being thixotropic.