Abstract
Moving particle semi-implicit method is widly used for the free surface and multi-phase flow analysis. In micro scale problems the surface tension is dominant. There have been two ways to calculate surface tension. One is based on CSF model, which is derived from continuum mechanics. The other is inter-particle force, which is similar to the inter-molecular force. The force is repulsive in short range and attractive in long range. We reveal the theoretical relation between this force and the surface tension coefficient. Oscillation of a droplet is analyzed by the present model. We also introduce the same inter-particle force between solid wall and fluid, which are represented by particles. Various wettabilities can be calculated by changing the ratio of inter-fluid and fluid-solid forces. The relation between the ratio and the contact angle is revealed theoretically. Droplet shape is calculated on a wall using the present model.
