The Flow and Decay Behavior of a Submerged Shear-Thinning Jet With Yield Stress

Abstract

The flow and decay characteristics of submerged jets of shear-thinning fluids with yield stress are studied. Numerical solutions to the governing mass and momentum conservation equations, along with the Herschel–Bulkley rheological model, are obtained using a finite-difference scheme. A parametric study is implemented to investigate the influence of flow inertia and rheology over the following range of parameters: Reynolds number, 50 ≤ Re ≤ 200; yield number, 0 ≤ Y ≤ 1; and shear-thinning index, 0.6 ≤ n ≤ 1. A large recirculation region exists for Newtonian and shear-thinning non-Newtonian jets. However, the extent and strength of the recirculation region substantially diminish with the yield number and, to a lesser extent, when the shear-thinning index is reduced from 1 to 0.6. Increasing the yield number beyond a critical value eliminates flow recirculation. The centerline velocity and momentum decay of shear-thinning jets with yield stress, in general, increase with the yield number. Velocity- and momentum-based depths of penetration, DPU, and DPM, respectively, are introduced and presented. DPU and DPM are the downstream locations corresponding to 90% decay in the initial centerline velocity and jet momentum, respectively. A substantial decrease in DPU and DPM is observed when the shear-thinning index is reduced from 1 to 0.6 for Y = 0. The presence of yield stress significantly reduces both DPU and DPM of submerged jets. The impact of shear-thinning on the decay characteristics of the jet is more pronounced at low yield numbers.

Numerical simulation and instability analysis of particles in liquid–solid concave‐wall jet using DPM‐RSM

“…The DPM with density difference was limited to study the plane‐wall jet 28 ; this study only analyzed the interaction between the dispersed particles of a vertical downward turbulent wall jet and the fluid turbulence in a uniform flow. The research showed that the DPM had the irreplaceable position for explaining the jet flow and the heterogeneous phase separation process 29–33 . The study about the heterogeneous separation process can apply the supplement theory of the concave‐wall jet.…”

“…(b) The instability vortices structures of jet separated from the concave-wall, reproduced from Stern et al (1997) and the heterogeneous phase separation process. [29][30][31][32][33] The study about the heterogeneous separation process can apply the supplement theory of the concave-wall jet.…”

An experimental study of buoyant jets : effects of viscoplasticity

“…They discovered that bifurcation was a phenomenon that occurred in high Schmidt (Sc) or high Prandtl (Pr) number jets and that it was brought on by the slower-moving fluid flowing nearer the edge of the jet. Hammad [23] numerically analyzed the flow and decay properties of submerged jets of shear-thinning fluids under yield stress. Using a finite difference method, they were able to derive numerical solutions to the governing mass and momentum conservation equations, using the Herschel-Bulkley rheological model.…”