Euler-Euler two-fluid simulation of turbulent bubbly jet flows

A set of closure models for the Euler-Euler two-fluid framework that was previously established for bubbly flows, in a variety of different geometries comprising pipes, bubble columns and stirred tanks by Rzehak et al. 2017 and Shi et al. 2018, is applied here to a turbulent bubbly jet. The closure models for momentum exchange comprise drag-, lift-, wall force-, virtual mass force-, and turbulent dispersion -force. The turbulence in the liquid phase is calculated using the SST k-ω model with an additional source terms to consider the effects of bubble induced turbulence. The open-source Computational Fluid Dynamics (CFD) tool OpenFOAM is used to perform these simulations.
Experimental data for validation are obtained from the previous work performed by Sun et al. 1986. In the experiment, a bubbly jet was injected from a round nozzle of diameter (D=5.08mm) oriented in vertical upward direction into a still water tank. These data featured a comprehensive set of observables including mean phasic velocities, liquid turbulent kinetic energy, and gas fraction along profiles in axial and radial directions. Primarily, the value of the bubble sizes is reported from the experiment, and this was used as an input parameter to the closure relations in the CFD simulation. Sample results of the present simulations are reported in the following wok. Closer to the nozzle they, are in good agreement with the measurement data along the axial and radial directions. At larger distances from the nozzle region, however, deviations are observed in the gas fraction. In an attempt to improve the prediction ability of the model, most likely the dispersion effects due to bubble-induced turbulence should be considered at an increasing gas injection from the nozzle.