APPLICATION OF THE LES METHOD TO THE OSCILLATING FLOW PAST A CIRCULAR CYLINDER

The oscillating flow of an incompressible fluid over a circular cylinder is investigated by solving the vorticity/stream-function version of the two-dimensional Navier Stokes equations using a finite-difference Large Eddy Simulation (LES) method. Two different subgrid scale (SGS) models are tested. They are the classical Smagorinsky model and Yoshizawa's Two-Scale Direct-Interaction Approximation (TSDIA) model, both of which require the input of constants in the specification of the subgrid scale viscosity. In addition, a solution was obtained with no subgrid scale model for comparison purposes. Yoshizawa's model is based on the combination of Kraichman's Direct Interaction Analysis (1964) with the separation of scales of mean (grid scale) and fluctuating (subgrid scale) fields. This TSDIA model has the length scale as a function of space and time so that it incorporates the effects of local time rate of change and advection of the resolvable field. Both models are applied to the classical problem of an oscillating two-dimensional flow over a circular cylinder at various KC values atβ =1035.Calculated lift and in-line force coefficients compare favorably with available experimental data for KC≤2 with the best solutions developed from the Yoshizawa model. The solution for KC>2 demonstrates that the two-dimensional model is inadequate to describe the flow accurately.