A comparison of structured and unstructured grid solutions for flow over a circular cylinder

Turbulence resolving calculations are performed on the flow past a circular cylinder at subcritical and supercritical conditions using a second-order, unstructured, finite-volume solver. Flow past a circular cylinder at the Reynolds numbers tested is representative of more complex geometries as it is three-dimensional, inherently unsteady, and results in massive boundary layer separation with turbulence. The primary goal of this research is to assess the performance of unstructured grids for turbulence resolving calculations such as large-eddy simulation and detached-eddy simulation. Comparisons are made to both experimental data and to numerical simulations using structured grids. For simulation at a Reynolds Number of 3900 the Strouhal number, time-averaged drag, back pressure, and recirculation zone length compare well with experimental results and results for similar computations conducted using structured grids. For Reynolds number 140,000 simulations, the time-averaged coefficient of pressure and drag fall within two separate sets of experiments and closely match a similar set of computations on structured grids using a high order solver.