Numerical Investigation of Three-Dimensional Laminar Wall Jet of Newtonian and Non-Newtonian Fluids

Abstract

Three-dimensional laminar wall jets of a Newtonian fluid and two shear-thinning non-Newtonian fluids were numerically investigated. The complete nonlinear incompressible Navier-Stokes equation was solved using a colocated finite volume based in-house computational fluid dynamics code. For each fluid, the computation was performed at three Reynolds numbers. The results showed that the streamwise velocity profiles for the Newtonian fluid became self-similar but the more shear-thinning fluid never achieved a self-similar condition. Significant differences were observed among the profiles for the various fluids in the inner region. Although the transverse and spanwise components of the velocity decreased substantially with increasing Reynolds number, the values for the non-Newtonian fluids were generally an order of magnitude larger than the corresponding values for the Newtonian fluid. Depending on the specific fluid and Reynolds number, the apparent viscosities were up to 4 orders of magnitude higher than the dynamic viscosity of water. Consequently, the spread of the jet in both the transverse and spanwise directions, decay of the maximum streamwise velocity, and the skin friction coefficient depend strongly on both Reynolds number and nature of the fluid. The results also show that the jet half-width in the transverse direction is significantly higher than in the spanwise direction.