Improvement of wetting calculation model on polygon wall in the MPS method

Abstract

MPS (Moving Particle Semi-implicit) method is developed for simulating free surface flow. For industrial applications of the MPS method, a polygon wall boundary condition model is a key technology to reduce calculation cost in complicated three-dimensional geometries. However, for the flow that surface tension is dominant, the existing polygon wall model does not show good results in some cases. The problem is that the existing polygon wall model cannot reproduce the wetting of a droplet with low contact angles correctly. In this paper, a new polygon wall boundary condition model is proposed to improve surface tension and wettability calculations. In the new model, the wall boundary condition of the pressure gradient is revised. Two-dimensional and three-dimensional calculations of a small droplet on the plane polygon wall are performed and the wetting with low contact angles is reproduced correctly by the proposed model. This model also works well with smaller numbers of particles. In the two-dimensional calculation, wetting of the droplet can be reproduced only by 25 particles for the contact angle of 30 degrees. In addition, the wetting simulation between the two parallel planes is performed and curved shape of the capillary bridge is successfully reproduced for the contact angles of 30, 60 and 90 degrees.