Sub-grid scale modelling and a-posteriori tests with a morphology adaptive multifield two-fluid model considering rising gas bubbles


Sub-grid scale modelling and a-posteriori tests with a morphology adaptive multifield two-fluid model considering rising gas bubbles

Meller, R.; Schlegel, F.; Klein, M.

The predictive simulation of gas-liquid multiphase flows at industrial scales reveals the challenging task to consider turbulence and interfacial structures, which span a large range of length scales. For simulation of relevant applications, a hybrid model can be utilised, which combines the Euler-Euler model for the description of small interfacial structures with a Volume-of-Fluid model as a scale-resolving multiphase approach. Such a hybrid model needs to be able to simulate interfaces, which are hardly resolved on a coarse numerical grid. The goal of this work is to improve the prediction of interfacial gas-liquid flows on a numerical grid with comparably large grid spacing. From the low-pass filtering of the two-fluid model five unclosed sub-grid scale terms arise. The convective and the surface tension part of the aforementioned contributions are individually modelled with multiple closure formulations. Those models are a-posteriori assessed in cases of two- and three-dimensional gas bubbles rising in stagnant liquid. It is demonstrated, that predictions on interfacial flows on coarse numerical grids can be improved.

Keywords: Large Eddy Simulation; Multiphase Flow; Sub-grid scale modelling; Multifield two-fluid model; Hybrid model

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Permalink: https://www.hzdr.de/publications/Publ-32356
Publ.-Id: 32356