Acoustic streaming outside spherical particles and parameter analysis of heat transfer enhancement

Abstract

Acoustic streaming effects can play an important role for promoting heat and mass transfer. Considering the viscous loss inside the viscous boundary layer on the particles surface, a numerical model for the acoustic streaming outside a two-dimensional spherical particle in a plane standing wave sound field is established, and the distribution characteristics of the acoustic streaming outside the particles are simulated by the numerical method of separation time scale. The reliability of the numerical simulation is verified by comparing the simulation results with the corresponding analytical solution. Based on this, we simulate the acoustic streaming distribution characteristics outside the particles under different Reynolds numbers and Strouhal numbers, and the acoustic parameters for heat transfer enhancement by acoustic streaming are analyzed. The numerical studies show that as the Strouhal or Reynolds numbers increase, the acoustic streaming region inside the boundary layer shrinks, but the shear force increases, and the vortex structure outside the particles increased from 4 to 8. when the particles are located in different positions of the plane standing wave sound field, the acoustic streaming has a rich flow pattern structure. The parameter analysis of the influence of acoustic streaming on convective heat transfer shows that the strong acoustic streaming motion formed by the acoustic waves with the small Strouhal number and large Reynolds number can greatly promote the heat and mass transfer process. For the small Strouhal number, the inner vortex in the viscous boundary layer is the main mechanism affecting the heat and mass transfer process. And increasing the Reynolds number is the most direct and effective means to strengthen the heat and mass transfer process The study helps to reveal the mechanism of acoustic to enhance the heat transfer of objects. In addition, the numerical method can be used to evaluate the external acoustic streaming characteristics of any physical model.