A New Source of Reaction - Diffusion Coupling in Confined Systems due to Temperature Inhomogeneity

Diffusion is often accompanied by a reaction or sorption which can induce temperature inhomogeneities. Monte Carlo simulations of Lennard-Jones atoms in zeolite NaCaA are reported with a hot zone presumed to be created by a reaction. Our simulations show that localised hot regions can alter both the kinetic and transport properties. Further, enhancement of the diffusion constant is greater for larger barrier height, a surprising result of considerable significance to many chemical and biological processes. We find an unanticipated coupling between reaction and diffusion due to the presence of hot zone in addition to that which normally exists via concentration.Comment: to be published in Phys. Rev. Let

LES of an Inclined Jet into a Supersonic Turbulent Crossflow: Synthetic Inflow Conditions

The main flow features generated by the gas-dynamic interactions of an inclined jet with a supersonic crossflow, such as barrel shock, shear layer, and counter-rotating vortex pair, were numerically captured by large-eddy simulation with subgrid scale (LES-SGS) stretched vortex model (AIAA Paper 2009-1511). In that study, the transition and spatial development of the jet were found to be strongly dependent on the inflow conditions of the crossflow. This result indicates that correct turbulent inflow conditions are necessary to predict the main flow characteristics, dispersion and mixing, of a gaseous jet in a supersonic, turbulent crossflow. This work presents a methodology for the generation of realistic synthetic turbulent inflow conditions for LES of spatially developing, supersonic, turbulent wail-bounded flows. The methodology is applied to the study of a supersonic turbulent flow over a flat wall interacting with an inclined jet. The results are compared with available experimental data, and the main flow characteristics and dominant vortical structures generated by the jet/turbulent-boundary-layer interaction are described