The objective of this study is to investigate the performance of a Reynolds Stress Model (RSM) with a two-layer model in the near-wall region in order to predict the mean velocity field, the turbulence characteristics and the heat transfer rate. The numerical predictions are validated against detailed measurements for the turbulent flow features and the surface temperatures with identical set-up.
The experimental set-up consists of an array of five wall-mounted cubes and only the third cube is heated. The cube is cooled by a low-velocity chaunel flow and an impinging jet from a circular nozzle above the third cube.
The time-averaged velocity field and the Reynolds stresses near the third cube were measured by PIV. The time-averaged surface temperature on the third cube was measured by a low-wavelength infrared imaging system. The measurement part of the present study was carried out at the Department of Applied Physics, Delft University of Technology, Delft, the Netherlands.
The linear pressure-strain model proposed by Launder and Shima (1989) is used in the RSM. The turbulent heat fluxes are modelled by the eddy-diffusivity hypothesis in analogy with the eddyviscosity hypothesis used for Reynolds stresses with a constant value of the turbulent Prandtl number. The mesh was refined enough near the solid walls (y+ ≈1) to solve all boundary layers. The commercial finite-volume code Fluent 6.1.22 was used.
A comparison between the results from the CFD predictions and the measurements shows a good agreement of this the complex flow field. The results revealed that there are several flow-related phenomena that affect cooling performance, such as stagnation points, separations, curvature effects and re-circulating wake flows.
13th International Heat Transfer Conference, Sydney, Australia, 13-18 August, 2006