Large eddy simulation of passive scalar in complex turbulence with flow impingement and flow separation

Abstract

In order to reveal unknown characteristics of complex turbulent passive scalar fields, large eddy simulations in forced convection regimes were performed under several strain conditions, including a flow impingement and a flow separation. By using the simulation results, relations between the dynamic and scalar fields were carefully examined. It was then confirmed that the scalar was transported by a large vortex structure near the examined regions wherever the mean shear vanished, though in the high shear regions, the scalar transport was governed by a coherent structure due to the high shear strain. In addition, a priori explorations were attempted by processing the data, focusing on the derivation of a possible direction for modeling the passive scalar transport in complex strain fields algebraically. The a priori tests suggested that an expanded form of the GGDH model introducing quadratic products of the Reynolds stresses was promising for general flow cases.