On Shadowing Effects in the Flow around the Group of Circular Cylinders in the Geotechnical Applications

Abstract

The purpose of the presented study is to investigate the influence of the distance between three infinite circular cylinders in a tandem group on their aerodynamic coefficients and the general flow pattern. The questions of the numerical simulation of viscous incompressible flow around a group of cylinders in the tandem arrangement are considered. The numerical study of the flow around the group of cylinders is based on unsteady Reynolds-averaged Navier-Stokes equations. The results are presented as a visualization of the instantaneous flow parameters and the dependencies of the averaged drag coefficients on the distance between the cylinders. Following the previous investigations, the flow parameters were chosen in a little-studied range, corresponding to the Reynolds number of 120 for a standalone cylinder. The distances between the centers of neighboring cylinders ranged from 1.1 to 6.0 cylinder diameters. Three characteristic flow patterns are distinguished depending on the distance between the cylinders. The first one is a steady-state flow similar to the flow around the standalone cylinder. This flow pattern is formed when the distance between the cylinders is less than three diameters. Increasing the distance between the centers up to four diameters produces the second flow pattern. The vortex street is formed behind the group while the flow between the cylinders remains steady. Further increasing the distance between the cylinders causes the formation of the third pattern when the flow between the cylinders becomes unsteady as well. The averaged drag coefficients for each cylinder in the group are obtained. The presented work helps better to understand the flow structure around the group of cylinders and can be used at the design stage in various engineering applications, including cooling towers, heat exchanger tubes, chimney stacks, marine platforms, and high-rise buildings.