Subgrid-Scale Modeling in Large-eddy Simulation and Its Application to Flow about Yawed Cylinder and Cavity Flow

초록

In this computation, Smagorinsky's eddy viscosity model combined with a truncated deductive model is used to represent the SGS stress fields in quadrilateral/hexahedral structured/unstructured grid system. The truncated deductive model considers the eddies immediately below the filter size, (which presumably lies within the inertial range, but not those near Kolmogorov scale, (, such that dissipation is not properly accounted for. Therefore it is assumed in this study that the Smagorinsky model describes the dissipation correctly, and the truncated deductive model ensures a smooth cascade process. To show the applicability of the proposed SGS model to the structured/unstructured grid system, two cases of the flow about a yawed cylinder and a cavity flow were numerically tested and compared with experimental data. The present results of the yawed cylinder were produced at a Reynolds number of 1.3(104 in the sub-critical range. As a second example of validating the code, three configurations of cavity (L/D=1.5, 2.0, 10.0) were used to simulate quasi-periodic flow patterns at a Reynolds number of 1.0(104. The sound generated from turbulent flows around the yawed cylinder and in the cavity was also computed using Lighthill's acoustic analogy. The LES results are compared to experimental data in terms of local characteristics such as base pressure coefficients, wall pressure and far-field noise spectra, which were measured in an acoustic wind-tunnel facility.