Bubble Formation in Yield-Stress Fluids Using a Coupled Level-Set and Volume-of-Fluid Method.

Baixu Cao,Shaobai Li,Lina Bai,Zhaochen Hu

doi:10.1021/acsomega.0c03390

Abstract

The bubble formation under the influence of orifice diameter submerged in yield-stress fluids was studied numerically using a coupled level-set (LS) and the volume-of-fluid (VOF) method and was in contrast with that seen in Newtonian fluids. The bubble formation process had a good consistency by virtue of comparing numerical simulation and experiment. The process of bubble formation could be divided into two parts, bubble expansion stage and stretch stage. The influence of orifice diameter and liquid rheological characteristics (consistency coefficient, flow index, and yield stress) on the bubble formation parameters (the bubble formation time, detachment volume, and aspect ratio) was investigated. The results revealed that the bubble detachment volume increases with the increase of orifice diameter, consistency coefficient, flow index, and yield stress. In different kinds of fluids, the formation time and detachment volume of bubbles in the shear-thinning fluid were the lowest, followed by the Newtonian fluid, and finally, in yield-stress fluids.

Highlights

The phenomenon of the bubble formation in fluids is widely used in a number of industrial processes, such as chemical, environmental, biological, and mineral processes
A deep-and-meaningful comprehension of bubble formation characteristics will be vitally favorable for completing the optimization design of gas−liquid two-phase related industrial processes
A legible graph describing the influence of the orifice diameter on the formation time and detachment volume of the bubble is shown in Figure 1a, where it can be seen that the bubble formation time decreases with the increase of the orifice diameter

Summary

Introduction

The phenomenon of the bubble formation in fluids is widely used in a number of industrial processes, such as chemical, environmental, biological, and mineral processes. Some researchers attempted to couple two interface tracking methods to simulate the motion characteristics of bubbles in the liquid phase.[16−18] Recently, Fan et al examined the formation volume and shape changes of bubbles in shearthinning non-Newtonian fluids through coupling the volumeof-fluid and level-set method (CLSVOF).[19]

Results

Conclusion