Abstract: An updated version of level set method without reinitializing step is designed to simulate the motion of a small volume of gas rising up to and bursting at an initially horizontal free surface. Accompanying topological changes of the gas-liquid interface, such features of the series of rotational motion as cavity, upward-jet, viscous-gravity-capillary waves along the merged interface are captured in the numerical examples. In some cases, smaller volumes of liquid may break off the jet at certain stage. In others, the free surface may roll up. In the tests, Reynolds number, Weber number, and gravitational acceleration are allowed to vary in wide ranges.

Key words: Level set method, gas-liquid interface, topological change