Forced convection flow and heat transfer across an in-line bank of circular cylinders

The common engineering problem of flow across an in-line bank of circular cylinders was studied using CFD to investigate the nature of flow and heat transfer of a Newtonian incompressible fluid under a two-dimensional laminar forced convection regime. The problem was modelled as a unit cell with symmetric and periodic boundary conditions, and the forced convection flow-governing equations were solved numerically using a finite volume-based solver (ANSYS Fluent). The study examined the dependence of local and global characteristics (streamlines, pressure and isotherm contours, individual and total drag coefficients, and average Nusselt number) on the following parameters: free-volume fraction (0.7 phi(f)0.99), Reynolds number (1Re40), and Prandtl number (0.7Pr100). The results reveal that, as the cylinder diameter becomes large relative to the pitch (i.e. as phi(f) decreases), friction drag across the cylinder surface increases, as well as pressure drag in the wake. Analogously, heat transfer improves and the Nusselt number increases as cylinder diameter-to-pitch ratio increases. The results were used to develop simple correlations for the drag coefficients and average Nusselt number.