A RANS-RSM based Eddy-Resolving Modeling of Bubble Plume Dynamics in Water Reservoirs and Channels*

Bubble plumes released into a quiescent water in a vertical reservoir and into a water cross-flow in a horizontal duct, both with rectangular cross sections, are computationally simulated within the Euler-Lagrange framework for two-phase flow computations. The described gas-liquid flow cases are characterized by a number of strongly coupled phenomena, such as bubble jet propagation, free surface flow, turbulence anisotropy induced secondary motion, and the varying interaction dynamics of the continuous water environment with the bubble dispersion. An appropriately extended differential near-wall Reynolds stress model in conjunction with a two-way coupled Euler-Lagrange approach describes the dynamics of unresolved subscale structures within the Sensitized Reynolds-Averaged Navier-Stokes (RANS) modeling strategy. The work focuses on assessing the predictive performance of this eddy-resolving turbulence model by comparing the computational results with existing reference studies and analyzing the accuracy of the time-averaged flow topology and associated turbulence structures. The study of the dynamic properties of the instantaneous character of the flow using the proper orthogonal decomposition reveals large-scale transient effects associated with the bubble jet.