Applicability of spatially periodic boundary conditions to a numerical computation of flow in a channel obstructed by an array of square rods

Abstract

AbstractTwo‐dimensional numerical computation is performed for an unsteady laminar flow. Spatially the periodic boundary conditions are adopted in the streamwise direction and the adequacy of this treatment is studied by varying the computational domain size. The following results were obtained. The Strouhal number and the lift coefficient fluctuation amplitude may change with the domain size for the same flow conditions. Therefore, numerical simulation for a unitary periodic flow field, a “cell,” is valid for limited flow conditions, which depend on the Reynolds number, the blockage ratio of the rod, and its pitch. Research was carried out on a condition in which the numerical solution is determined uniquely, i.e., the calculated results do not change with the domain size, by paying attention to the change in the phase difference of the flow patterns between neighboring cells. The Strouhal number, the drag coefficient, and the lift coefficient fluctuation amplitude increase considerably with the blockage ratio in the calculated results. The lift coefficient fluctuation amplitude decreases slightly with the increase of the rod pitch. © 2004 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(6): 357–370, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20027