Numerical simulation of flow past a blunt body.

摘要

Flow past a blunt body at high Reynolds number was simulated by an unstructured flow solver (Cobalt). Two cylinders with circular and square cross sections were selected as the test cases. The flow field of interest at high Reynolds number contains several phenomena such as turbulent separation, reattachment, and unsteady vortex shedding, which are commonly found in more complex flow fields. However, they are difficult to simulate by traditional Reynolds averaged approach and infeasible for Direct Numerical Simulation at this time. Even though Large Eddy Simulation (LES) can be used for this application, this approach has some inefficiencies and uncertainties. Therefore, in this effort Detached-Eddy Simulation (DES), which functions as Reynolds averaged in near wall region and turns to LES far from the wall is used. This procedure requires fewer grid points compared to LES. To assess the quality of solution, the results are evaluated by comparison with other numerical and experimental results. In addition, trip functions and laminar solution were also investigated in some cases. Most of the results for circular cylinder compare well with the experimental data and better than other published numerical results. However, the results of square cylinder are not quite as satisfactory. The primary reason for this inaccuracy is the grid system, which is much more challenging to generate.