The vital importance of dispersive fluxes on turbulent flow and pollution ventilation in street canyons

Abstract

Using a parallelized LES model (PALM) the importance of additional transport terms generated by applying time and area averaging on the fluxes of resolved scale variables (i.e. dispersive momentum (scalar) fluxes) compared to conventional turbulent momentum (scalar) fluxes in different street canyons is investigated. It is shown that the role of dispersive fluxes in the total flux is much greater than considered before (even more than conventional turbulent fluxes); if the true effect of dispersive fluxes is not taken into account, a large amount of the total flux would be lost and there would be no consistency between the pollutants concentration and the rate of their production and exit. © 2021 Elsevier B.V.