基于SPH方法的低韦伯数下三维液滴碰撞聚合与反弹数值模拟研究

光滑粒子流体动力学方法（SPH方法）作为纯拉格朗日粒子方法,可以有效避免网格法在模拟大变形过程中带来的网格扭曲等缺陷,适合模拟含大变形的液滴碰撞聚合与反弹过程。该文基于Ott和Schnetter提出的修正SPH方法,利用有限差分与SPH一阶导数相结合的方法处理粘性项中的二阶导数问题,进行Couette流算例验证,数值解...

SIMULATION OF COALESCENCE AND BOUNCING OF THREE-DIMENSIONAL DROPLET COLLISIONS WITH LOW WEBER NUMBERS BASED ON SPH METHOD

As a Lagrangian particle method,Smoothed Particle Hydrodynamics(SPH) method can deal with a large deformation without mesh distortion effectively,which is different from traditional grid-based methods.So it is one of the most suitable methods to solve the problems such as coalescence and bouncing of colliding droplets.Based on the modified Ott-Schnetter SPH method,the solving equations are presented in this paper in which the second derivative item in viscosity is treated with combining a standard SPH first derivative with a finite difference approximation of a first derivative.The Couette flow is simulated and the numerical results by this method are in close agreement with the series results.Molecular cohesive pressure within a van der Waals(vdW) model is used to deal with the surface tension,which is validated via the evolution process of a liquid droplet from initial square shape under surface tension.Finally,three-dimensional problems of head-on and off-centre binary collision dynamics of two equal size tetradecane droplets are simulated.Meanwhile the collision of two immiscible droplets with a large surface tension difference,namely,a water droplet and a diesel oil droplet,is also investigated.The numerical results all show a good agreement with the experimental results.It indicates that this method is suitable to solve problems with large deformations such as collision of droplets.