A numerical study of the impact of surface roughness on heat and fluid flow past a cylindrical particle

This work is devoted to a two-dimensional numerical study of the influence of surface roughness on heat and fluid flow past a cylindrical particle. The surface roughness consists of radial notches periodically distributed on the cylinder surface. The roughness was varied using different notch shapes and heights. The Navier-Stokes equation and conservation of energy were discretized using the Finite Volume Method (FVM) onto a fixed Cartesian grid, and the Immersed Boundary Method (IBM) with continuous forcing (Khadra et al. Int. J. Numer. Meth. Fluids 34, 2000) was used to simulate heat and gas flow past a cylindrical particle with a complex geometry. A polygon and the Sutherland-Hodgman clipping algorithm were used to immerse the rough cylindrical particle into a Cartesian grid. The influence of the roughness on the drag coefficient and the surface-averaged Nusselt number was studied numerically over the range of Reynolds numbers 10 <= Re <= 200. Analyzing the numerical simulations showed that the impact of the roughness on the drag coefficient is negligible in comparison to the surface-averaged Nusselt number. In particular, the Nusselt number decreases rapidly as the degree of roughness increases. A universal relationship was found between the efficiency factor E-f, which is the ratio between Nusselt numbers predicted for rough and smooth surfaces, and the surface enlargement coefficient S-ef. (C) 2012 Elsevier Masson SAS. All rights reserved.