Low Reynolds number mass transfer past regular square arrays of cylinders in cross flow

Abstract

Computational results were obtained for low Reynolds number steady and fully developed cross flow with mass transfer past an infinite regular square array of cylinders. For a fixed porosity of 0.5 the Reynolds and Schmidt numbers and the orientation of a forcing term (representing the driving pressure gradient) were made to vary in a broad range, and their influence on local and overall mass transfer was investigated. Both uniform mass flux and uniform concentration conditions at the cylinder-fluid interface were considered. In the Reynolds number range investigated (from Re = 10–4 to Re ≈ 102, which is the largest value for which steady-state conditions can conservatively be assumed), an extremely complex dependence of the local and mean Sherwood number on the forcing term orientation was observed, which became increasingly strong and Schmidt number-dependent as the Reynolds number increased. For all Schmidt and Reynolds numbers considered, the mean Sherwood number correlated well with the Péclet number, exhibiting a flat behavior up to Re ≈ 2 and a ∼0.25-power law increase for larger Re. Boundary conditions significantly affected local Sherwood numbers, but much less corresponding mean values. The applicability of existing heat transfer correlations for tube banks to the present conditions was critically discussed.