Simulation of a Water Droplet on Horizontally Smooth Surface Using Quasi-Molecular Modelling

Abstract

We developed a method based on quasi-molecular modelling to simulate the fall of water drops. Each quasi-molecule was a group of particles that interacted in a fashion entirely analogous to classical Newtonian molecular interactions. When a falling water droplet was simulated at low impact velocity, the droplets moved periodically (i.e. the droplets moved up and down for a certain period, then stopped moving and reached a steady state), spreading and recoiling without splash or break-up. Spreading rates of falling water droplets increased rapidly as time increased until the spreading rate reached its steady state at time t ~ 0.4 s after the impact. The droplet height above the surface decreased as time increased, remained constant after the droplet diameter attained a maximum value and reached its steady state at time t ~ 0.4 s after the impact. When impact velocities were varied by changing the setting of the vertical height (i.e. at 0.25, 1.25 and 6.00 cm), spreading rates increased with increasing impact velocity. However, the droplet height above the surface was not affected by increasing impact velocity.