Large eddy simulation of turbulent channel flow with mass transfer at high-Schmidt numbers

Large eddy simulation (LES) of turbulent channel flow with mass transfer has been performed to investigate the effect of the Schmidt number on the turbulence behaviors. The three-dimensional filtered Navier–Stokes equations and the concentration equation are numerically solved using a fractional-step method. Dynamic subgrid-scale (SGS) models for the turbulent SGS stresses and mass fluxes are employed to closure the governing equations. The objectives of this study are to examine the reliability of the LES technique for predicting the turbulent mass transfer at high-Schmidt numbers and to analyze the behavior of turbulent mass diffusion from a solid boundary to the adjacent shear flow at different Schmidt numbers. Fully developed turbulent channel flows with constant difference of concentrations imposed on different walls are calculated for a wide range of the Schmidt number from 0.1 up to 200 and the Reynolds number 13 800 based on the centerline mean velocity and the half-width of the channel. To show the effects of Schmidt number on the turbulent mass transfer, mean and fluctuating resolved concentrations, mass transfer coefficient, turbulent mass fluxes, and some instantaneous flow and concentration fields are exhibited and analyzed.