The effect of free-stream turbulence on turbulent boundary layers and convective heat transfer from flat plates
Abstract
The present work investigates the effect of free-stream turbulence (FST) on turbulent boundary layers and forced convective heat transfer from flat plates. High resolution, 2-D and 3-D, steady Reynolds-Averaged Navier-Stokes (RANS) simulations using Computational Fluid Dynamics (CFD) techniques were performed to analyze the influence of different free-stream conditions, such as turbulence intensity (TI), integral length scale (Lu) and free-stream velocity (Uo) on local and total skin friction and convective heat transfer coefficients (CHTC), as well as on turbulent boundary layer parameters (boundary layer thickness and momentum thickness). The present study shows that the Shear Stress Transport (SST) k-ω model with the low Reynolds number (Re) approach is the most suitable model for representing incident turbulent flow over isothermal flat plates, since it provides the correct skin friction and Nusselt number for turbulent boundary layers, along with the appropriate streamwise TI decay through the numerical domain. Using the results, a set of non-dimensional correlations for local and total skin friction, momentum thickness, local and total CHTC were developed. These are simple and useful tools for the prediction of skin friction and forced convective heat transfer from flat plates under FST, which can be helpful for many engineering applications such as photovoltaic systems.