微液滴振荡过程的光滑粒子动力学方法数值模拟

Numerical simulation on oscillation of micro-drops by means of smoothed particle hydrodynamics

本文对传统的光滑粒子动力学方法进行了改进,改进的光滑粒子动力学方法对传统粒子方法中的核梯度进行了修正,采用了一种新型的核函数和离散格式,应用改进的光滑粒子动力学方法对微液滴振荡过程进行了数值研究.研究了不同纵横比和雷诺数(Re)下振荡阻尼与振荡的周期、振幅与Re数的关系.研究表明:对于纵横比λ4时的微液滴振荡过程,其他参数恒定不变的前提下,Re数越大,液滴形状变化越剧烈,波的阻尼作用越弱,液滴振荡周期变长;在Re数一定的前提下,随着液滴初始的纵横比的增大,液滴振动的振幅增大,液滴振荡的周期变长.

In this paper, we present a modified smoothed particle hydrodynamics （SPH） method. SPH is a Lagrangian meshfree particle method, and it is attractive in dealing with free surfaces, moving interfaces, and deformable boundaries. The improved SPH method modifies the kernel gradient in the traditional SPH method with a new kernel function and a modified SPH discrete form. Use of improved smoothed particle hydrodynamics is made to carry out numerical analysis on micro liquid drop oscillation process. The study focuses on the relation between the micro liquid drop oscillation damping and the oscillating period and amplitude in different aspect ratio and Re number. It is shown that for the micro liquid drop oscillation process with aspect ratio λ 6 4, under the circumstance of constancy of other parameters, the larger the Re number, the more intense the change of liquid drop’s shapes, the weaker the damping effect, and the longer the period of liquid drop’s oscillation. Under the circumstance of constancy of Re number, as the initial aspect ratio of liquid drop increases, the amplitude of liquid drop oscillation is stronger, and the period of liquid drop’s oscillation is longer.