Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

Different approaches for numerical simulations of multiphase flows have been developed, e.g., Volume-of-Fluid methods (VoF) for free surface flows and Euler-Euler (EE) methods for disperse flows. Nevertheless, most industrial applications involve interfacial structures, which have different morphologies. Therefore, hybrid approaches combining resolved interfaces between the gaseous and liquid phases with EE methods would be desirable. A recent development with promising results is the GENTOP concept (Hänsch et al., 2012), which is based on the multi-fluid concept and statistically resolved interfaces that are formed by a separate liquid and gas phase. The present contribution investigates the differences between VoF methods and the GENTOP framework using the example of a buoyancy-driven motion of a single bubble. Different CFD solvers are compared as well as different density ratios, Eötvös numbers, Morton numbers and grid resolutions. Finally, all results are checked against experiments and data obtained by more advanced methods, e.g., level-set methods. For instance is known from one-fluid approaches (e.g. VoF) that at least 20 – 30 cells per bubble diameter are required to reflect the bubble motion sufficiently. Despite a much coarser grid resolution, GENTOP shows a good agreement with experimental results.