A locally redistributed level-set method for numerical simulation of thin interface structures

The level-set method performs well when it captures relatively thick interface structures, but may not properly resolve thin interface structures when their sizes are comparable to or smaller than grid sizes. With coarse grids, these thin interface structures are lost through non-physical breakup during simulation. We propose a locally redistributed level-set method to sustain thin structures with reasonable grid resolution. The present method distributes additional level-set functions at the regions where two interfaces of a structure are about to contact. This method captures thin interface structures smaller than grid sizes. Moreover, it identifies adjacent interfaces separately, and enables an accurate calculation of surface tension. Numerical simulations are performed for binary droplet collisions at relatively high Weber numbers, and show that thin interface structures are well captured and their interface dynamics is accurately predicted.