LES of the flow past a rectangular cylinder using the immersed boundary concept

Incompressible turbulent flow past a long square cylinder is investigated using large eddy simulations (LES). Results are presented and compared with available experimental databases for a Reynolds number Red=22000. The problem served as one of the validation cases for the development of a numerical code designed for efficient, parallel, three-dimensional N-S computations in complex geometrical configurations. In contrast with previous studies, the geometrical definition of the problem is established by the immersed boundary concept (IMB) while pressure solution is performed by a fast, fully parallel direct pressure solver. Calculations were performed with the widely applied Smagorinsky turbulence model and the filtered structure function model (FSF) which has not been previously applied to the flow case under consideration. In order to assess the potential of LES at its lowest (RANS), and highest (DNS) limit, different numerical resolutions were examined. Depending on the available resolution, either no-slip conditions or a modified Werner and Wengle approximate wall boundary condition was used. The predicted mean velocity and fluctuation profiles, force statistics and Strouhal numbers were found to be in very good agreement with the experimental data sets. Analysis of the results indicates that for time varying bluff-bodies flows that involve complex flow phenomena, successful large eddy simulations are not just possible, but can also achieve an excellent quality of results at a relatively low cost.