An enhanced semi-implicit particle method for simulating the flow of droplets with free surfaces

The accurate modeling of the surface-tension on free surfaces remains a challenging problem in meshfree particle methods. Recently, Matsunaga et al. (2020) have made an important step forward toward addressing this issue by introducing a moving surface mesh to represent the free-surface boundary in 2D. However, the surface mesh makes it difficult to extend this methodology to 3D and to treat topological changes in free surfaces. This study aims to extend this methodology to 3D and restore the capability of the model to simulate topological changes by carefully detecting the free-surface particles. In this situation, the problems regarding fluctuated free-surface boundaries and the dynamic intersection of a free surface with a wall boundary arise. To resolve these problems, a new particle shifting method in the surface normal direction is proposed for the free-surface particles to reduce fluctuations. A new contact angle model is proposed to compute the intersection point of a free surface and a wall boundary. In this manner, an enhanced particle method suitable for simulating the dynamics of liquid droplets with possible topological changes in 3D is developed. Eight numerical examples verified the developed method and demonstrated the enhancement of the new particle shifting technique. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The accurate modeling of surface tension on free surfaces remains a challenging problem in meshfree particle methods. This study aims to extend a recent methodology to 3D and restore the capability of simulating topological changes. A new particle shifting method and contact angle model are proposed to address the problems of fluctuated free-surface boundaries and dynamic intersection with a wall boundary. The developed method is validated through numerical examples and shows improvement compared to previous techniques.