TURBULENT FLOW AND HEAT TRANSFER FROM A SINGLE HEATED CUBE PLACED IN A MATRIX OF UNHEATED CUBES: A DNS STUDY

Direct numerical simulations (DNS) of a thermally developing and hydrodynamically developed flow over a heated wallmounted cube placed in a matrix of non-heated cubes has been carried out. The cubes are arranged in a tandem fashion. A finite-volume methodology In-house code is used to solve the Navier-Stokes and energy equations. The Reynolds number for the present simulations are taken to be constant (3854) based on the cube height and inlet velocity. The flow dynamics and the associated heat transfer has been explored in details. Results have been analysed based on instantaneous Q criteria, the time history of Nusselt number at each face of the cube and its probability distribution function (PDF). The bimodal behaviour of horseshoe vortex has been confirmed. The presence of turbulent horseshoe vortex, top, side and arc vortices are visualized clearly through the analysis of time-averaged Q criteria. Moreover, the size of the recirculation bubble associated with these structures is determined through analysing the time-averaged streamlines in the mid-spanwise plane. Finally, the time-averaged wall shear stress and Nusselt number at each face of the cube is explored, which is most important in design considerations.