A coupled lattice Boltzmann/finite volume method for turbulent gas-liquid bubbly flows

Abstract

[EN] A simulation method for large eddy simulations (LES) of dispersed gas-liquid bubbly flows based on an Eulerian-Eulerian (E-E) model is presented. A volume averaging approach is used resulting in a set of conservation equations for each phase. The liquid phase is predicted using a lattice Boltzmann method, while the gas phase is modeled by a finite volume method. Interface terms between the phases result in a two-way coupled system. Both methods are formulated on a shared Cartesian grid similar to the concept in [1], which facilitates the exchange of coupling terms between the two solvers and an efficient implementation on high-performance computing (HPC) hardware. This coupled multiphase approach combines the advantages of the lattice Boltzmann (LB) method as an efficient prediction tool for low Mach number flows with those of a finite volume method used for the modeling of the phase with larger density changes by solving the Navier-Stokes equations. To accurately model the turbulent motion of the liquid phase on all resolved scales, a cumulant-based collision step for the lattice Boltzmann method [2] is combined with a Smagorinsky sub-grid-scale turbulence model. In the finite volume solver, the effect of the sub-grid-scale turbulence is incorporated according to the MILES approach. For the validation of the new method, large-eddy simulations of turbulent bubbly flows are performed. The accuracy of the predictions is evaluated comparing the results to experimental reference data for a generic test case, for which good agreement is found. The applicability of the method will be demonstrated for a bubbly turbulent channel flow, which mimics the phenomena in the electrochemical machining (ECM) process.