Numerical simulation of turbulent flow in channels with three-dimensional blocks

Turbulent flow over surfaces roughened by simple geometric elements, such as discrete three-dimensional pro turbulences, continue to be of interest in fluid engineering from several perspectives, regular roughness elements are routinely used for heat transfer enhancement. They are also used to study surface roughness effects, in general, as they easily reproduced in the laboratory and modeled in numerical experiments. The characteristics of a turbulent flow in channels with three-dimensional blocks are investigation in the context of surface roughness effects. Reynolds-averaged, Navier-Stokes equations, coupled with the kappa-omega turbulence model with near wall treatment are solved by a finite-volume method. The space-averaged velocity profile exhibits a logarithmic region, with a roughness function that varies logarithmically with the roughness Reynolds numbers. At sufficiently large distance from the roughness elements, the effect of the individual elements vanishes and the net effect on the velocity profile is felt as reduction in the constant, beta, known as the roughness function, depends not only on the roughness size but also on its geometry. The different block arrangements exhibit quite distinct flow characteristics but the differences tend to vanish as the block height decreases. In general, Reynolds-averaged numerical model successfully describes the principal features of wall roughness that have hitherto for been the purr view of experimental correlations. [Mehdi Ahmadi, Iman Soleimani Marghmaleki. Numerical simulation of turbulent flow in channels with three-dimensional blocks. Life Science Journal. 2011;8(4):511-516] (ISSN:1097-8135). http://www.lifesciencesite.com.