Crown behavior in drop impact on wet walls

Axisymmetric computations of drop impingement on walls with a pre-existing liquid film are reported. A high-density-ratio lattice-Boltzmann model is employed for the computations. The focus of the work is on the behavior of the crown that forms as a result of impingement. When the crown forms, its base radius and height grow with time. Subsequently, it may break up. The influence of wall liquid film thickness, and surrounding gas density and viscosity on crown behavior is investigated. When the liquid film is thin, it is observed that the rate of increase of the radius and height of the crown increases with increasing film thickness. The breakup of the crown is delayed. On thicker films, the rate of increase decreases with increasing film thickness, but the breakup is further delayed. When either gas density or viscosity is increased, the rate of increase of the radius and height decreases and breakup is delayed. (c) 2007 American Institute of Physics.