Some numerical considerations in the simulation of low-Ma number hydrogen/air mixing layers

In this work numerical simulations of hydrogen/air mixing are conducted which demonstrate the generation of spatial pressure gradients arising from the diffusion of species (hydrogen versus air) of high molecular weight disparity. Convective velocities arising as a result of the spatial gradients have been evaluated with respect to molecular weight ratio between stratified layers in coflow and stationary diffusion layers. The implications of results for the spatially-constant thermodynamic pressure assumption for low-Mach-number flows are discussed. Additionally, the impact of the choice of diffusion model on the results has been assessed.