Visualization of interface instabilities in two-phase flow

Abstract

The simulation of two-phase flow is a very important topic which influences many modern fields of research, such as the development of combustion engines and turbines. Hence, it is a crucial task to analyze these simulation results. To this end, this thesis introduces new ideas for the calculation of the change in size of the surface area of droplets, the so-called interface stretching, and its visualization. As underlying vector field, both the surface tension force, as well as the actual velocity field provided by the simulation are used. Reconstructing the interface of a Volume-of-Fluid (VOF) field using PLIC (Piecewise Linear Interface Calculation), the changes of the interface can be calculated using different methods and are visualized using various techniques. Coloring corresponding to the stretching or contraction of the surface, as well as vector glyphs can be used to find areas of interest and provide enough information that rough estimates of the transformation of the droplets can me made. Especially using the surface tension force, local changes, such as deformation and changes in topology can be predicted.