Towards numerical modelling of surface tension of microdroplets

Abstract

The chapter combines the hybrid method for advecting the interface and the continuous surface force (CSF) model within a finite-volume, collocated grid scheme. A number of validation tests are performed that involve flows under gravity and problems where surface tension is important. The flee-surface test involves the initial stages of a dam break and the results are compared with the experimental data of Stansby. The second test calculates the pressure rise because of surface tension inside a cylindrical liquid rod and the final test involves the simulation of a gas bubble rising in mineral oil. The computed results for the terminal velocity of the bubble are then compared to the experimental observations of Hnat and Buckmaster. Surface tension can be a significant force at the micro scale, and the two final tests are the key steps toward reliable modeling of the surface tension phenomena in Microsystems. A parallel, hybrid volume-of-fluid and tangent transformation method is combined with the continuous surface force (CSF) model and successfully implemented in a collocated grid framework. The formulation ensures that the calculation of the volumetric surface tension force is consistent in the pressure and momentum equations, reducing spurious currents significantly.