ISSN Online: 2379-1748
8th Thermal and Fluids Engineering Conference (TFEC)
THREE-DIMENSIONAL FLOW TRANSITION AROUND A HEATED DIAMOND-SHAPED CYLINDER IN MIXED CONVECTIVE FLOW REGIME: A DNS STUDY
Abstract
The three-dimensional flow transition is studied in the wake of a heated diamond-shaped cylinder using air (Prandtl number, Pr = 0.7) as a working fluid. The cylinder is exposed to free-stream crossflow at an angle perpendicular to gravity. In this study, a non-Oberbeck–Boussinesq compressible model is used to capture the changes in transport properties and thermal straining of the fluid particles on large-scale heating. The heating level is defined as over-heat ratio ε = (Tw − T∞)/T∞, where Tw and T∞ are the uniform surface and the
surrounding temperatures. A flux-based particle velocity upwind-modified+ (PVU-M+) scheme is employed
to solve compressible flow governing equations (in a body-fitted coordinate system). All computations are
performed at a low Mach number (M = 0.1). For model validation, the obtained values of the time-averaged
drag coefficient (CD) and the Strouhal number (St) are compared with the values reported in the literature at Reynolds numbers Re = 100 − 200 and ε = 0. In this investigation, it is observed that the buoyancy effect increases by increasing the ε value, and the flow field around the cylinder becomes asymmetric. At Re = 200, significant changes in the vorticity structure shape and their spanwise wavelength are observed in the cylinder wake for ϵ values ranging from 0 to 1. The heating effects are observed in the time histories of
global flow parameters such as force coefficients (CD and CL) and Nusselt number (Nu).