Vortices and heat flux around a wall-mounted cube cooled simultaneously by a jet and a crossflow

Vortex morphology and heat transfer over a wall-mounted heated cube in an in-line array, cooled simultaneously by a crossflow and a normally impinging round jet, have been studied by conjugate large-eddy simulations. The interaction of the two streams and the cubes leads to the formation of complex vortical structures that govern heat removal from the cube surface. The strongest and the most evenly distributed cooling were found on the cube top and the front face. The heat flux on the side faces is lower in the zones where the flow separates, while it increases downstream where a fresh fluid from the crossflow flushes the faces. The separation on the back face of the cube creates an arch vortex, which dictates the heat transfer from that face. Despite its persistence and relative steadiness, significant nonuniformity of the temperature field has been detected on the rear face, characterised by the time meandering of hot spots. Vortex rings, created in the jet shear layer before its impact on the cube, break up upon impingement, leading to the re-establishing of the thermal boundary layer, and the consequent enhancement of heat transfer. The turbulent heat flux and its budget correlate well with the corresponding turbulent stress components.