Numerical simulation of flow past a bluff body of two different shapes using gradient smoothing method with unstructured grids

In this paper, flow across a bluff cylinder with circular and equilateral triangular sections shapes at low Reynolds number (10 ≤ Re ≤ 250) is numerically investigated using the gradient smoothed method (GSM). The method was originally developed based on unstructured grids, which could be generated easily for complicated domains. For solving the incompressible flow, artificial compressibility terms are introduced in Navier-Stokes equations. The spatial derivatives of convective and viscous fluxes are obtained using the gradient smoothing operation. And the time marching is implemented based on the dual time stepping technique. The situations of steady flows with Re = 10-40 and unsteady flows with Re = 50∼250 are simulated. Analysis of the drag coefficients, root mean square (rms) value of lift coefficients and Strouhal number of circular and triangular cylinders has been carried out. Compared with both experimental and numerical reference solutions in the literatures, the accuracy of GSM results has been demonstrated.