Surface Tension Dominated Flows: Observations with ANSYS FLUENT
Sprache des Vortragstitels:
Ansys Multi-Phase Flows Workshop
Sprache des Tagungstitel:
In metallurgical processes such as continuous casting of steel, gas injection is used to influence the flow or to trigger chemical reactions. Nucleation, growth and transport of bubbles have to be treated specially in low pressure regions. Hence two phase flows are an important topic. Whenever the interaction between the gaseous phase and a wall is of interest or the two phase flow regime is unknown, it is essential to resolve the interface between the two phases. Thus the volume of fluid (VoF) model implemented in FLUENT is an interesting tool to investigate these flows.
First, a model of a single gas injection at a wall is considered. This configuration also represents a bubble nucleation process at a wall. The calculation of this test case resulted in a highly deformed interface combined with high parasitic velocities in both domains ? gaseous and liquid ? and showed poor convergence. The main problem seems to be the grid influence on the calculation of the surface tension as well as the deformation.
A second configuration is considered in order to further investigate the numerical phenomena of the surface tension model. A 2D bubble in a resting fluid without gravitation is calculated. Even in this simple setup the bubble is deformed unphysically affected by the mesh. Parasitic flows in the liquid phase occur. In this test case the forces are calculated according to the FLUENT manual. The results show that the implementation of the interface curvature calculation as well as the calculation of the surface tension are the main reasons for the parasitic flows. These effects even increase with a finer mesh resolution. Finally, OpenFOAM calculations are presented and compared to the results obtained with FLUENT.