A Large-eddy Simulation of the Turbulent Flow in the Vicinity of an Upright Wall-mounted Half Cylinder and Aerodynamic Sound Prediction

초록

The turbulent flow approaching an upright wall-mounted half cylinder has been numerically investigated by using Large-Eddy Simulation. The formation and the downstream transport of horse-shoe vortex are numerically simulated and compared with experimental data. The interactions between horse-shoe vortex formed by re-orientation of incoming vorticity and the Strouhal vortices in the near wake of the half cylinder are also examined in this study. The governing equations are formulated in terms of a structured, curvilinear grid system to accommodate the truncated deductive model proposed by Lee(1992) for the subgrid-scale turbulent motions. The present results are produced at a Reynolds number of 8.0(103, based on the cylinder diameter. The far-field sound is also computed using Lighthill's acoustic analogy. This LES results are examined with our experimental data in terms of both the global and local characteristics such as mean drag and base pressure coefficients, vortex shedding frequencies, wall pressure and far-field noise spectra, which are measured in an acoustic wind-tunnel facility.