A two-equation subgrid-scale model for Euler-Euler large eddy simulation of two-phase flows in bubble column reactors

Identificador:  imarina:9469326

Handle: https://hdl.handle.net/20.500.11797/imarina9469326

Autors:  González, D; Vernet, A; Gourich, B; Stiriba, Y

Resum:
This work presents a Euler-Euler Large Eddy Simulations (LES) two-fluid model for dispersed turbulent flows applied to simulate gas-liquid two-phase flows in bubble column reactors. The model is based on the one-equation model for the subgrid-scale (SGS) turbulent kinetic energy and develops a new transport equation for the subgridscale turbulent energy dissipation rate which avoids calculating the SGS turbulent length without referring to mesh size and offers the possibility to model more accurately physical phenomena at the SGS level. In this way, the amount of the SGS energy dissipation is employed to improve the modeling of the bubble induced turbulence (BIT). The BIT closure terms components are incorporated to the transport equations of the SGS turbulent kinetic energy and dissipation rate as a source term and the other component is added to the effective viscosity as a contribution of turbulence interaction. The new Euler-Euler two SGS model was implemented in the open-source OpenFOAM code and employed to simulate a two-phase bubble column reactor flow. The predicted liquid velocities and the turbulent kinetic energy are in good agreement with experimental data both in the core and the near-wall regions. The numerical simulations confirm that the energy spectra of the resolved liquid velocities in churn-turbulent regime follows the classical-5/3 law for low frequency regions and are close to-3 for high frequencies. To the best of our knowledge, this is the first use of a transport equation for SGS dissipation rate of turbulent kinetic energy in two-phase flows.