Numerical simulation of a single drop impact on liquid surface using particle method

The process of single liquid drop impact on thin liquid surface is numerically simulated with Moving Particle Semi-implicit (MPS) method. The mathematical model involves gravity, viscosity and surface tension. The model is validated by simulation of the experiment of Wang and Chen (2000) and Manzello and Yang (2002). It is found that the dynamic processes after impact are sensitive to the liquid pool depth and the initial drop velocity. In the cases that the initial drop velocity is low, the drop will be merged with the liquid pool and no big splash is seen. If the initial drop velocity is high enough, the dynamic process is related to the liquid depth. If the liquid film is very thin, a bowl-shape thin crown is formed immediately after the impact. The total crown subsequently expands outward and breaks into many tiny droplets. When the thickness of the liquid film increases, the direction of the liquid crown becomes normal to the surface and the crown propagates outward. It is also found that the radius of the crown is described by a square function of time: rc=[c(t - t0)]0.5 as shown by Weiss and Yarin (1999). When the liquid film is thick enough, a crown and a deep cavity inside it are formed shortly after the impact. The bottom of the cavity is initially oblate and then the base grows downward to form a sharp corner and subsequently the corner moves downward. (author)