Abstract
Drag in a row of equally-spaced circular cylinders arranged along the centerline of a straight duct is critically examined by a series of high-resolution numerical simulations based on an immersed boundary method. Time series of the pressure gradient required to maintain a constant flow discharge which is an indicator of the macroscopic resistance to the flow are obtained from the numerical experiment.It is revealed that the resistance is maximized when the surfaceto-surface distance between neighboring cylinders is close to the cylinder diameter,irrespective of the bulk and stem Reynolds numbers of the flow. The pressure gradient is found to be roughly scaled with the effective duct width L. and the bulk-mean veloicty Ub. , which take it into account that the actual cross-sectional area of the flume is decreasd by the presence of the cylinders. The present study suggests that the influence of the stem Rynolds number needs to be reflected for a better scaling of the drag.
