A LARGE-EDDY SIMULATION OF THE NEAR WAKE OF A CIRCULAR-CYLINDER

The formation and the downstream transport of the Strouhal vortices in the near wake of a circular cylinder are investigated using the large -eddy simulation (LES) method. The governing equations are formulated in curvilinear coordinates to accommodate a nonorthogonal grid with fo rmal development of a dynamic model to account for the subgrid turbule nt scales. Results were produced with and without use of the model. Th e focus of the investigation is at a subcritical Reynolds number of 56 00. Using the dynamic model, the LES results compared best to the publ ished experimental data in terms of bath the global and local wake cha racteristics such as the drag and base pressure coefficients, shedding and detection frequencies, peak vorticity, and the downstream mean ve locity-defect and Reynolds stresses. The results further showed stream wise filaments that connect subsequent Strouhal vortices. Qualitativel y, the time-averaged Reynolds stresses of the formation region reveale d similar symmetric characteristics over the range 525 less than or eq ual to Re less than or equal to 140,000.