Abstract
We examined performances of LESs by using an open source CFD code, OpenFOAM, which has been widely used all over the world for numerical turbulence simulating, to represent dynamic behavior of drag and lift forces on a cylinder under critical Reynolds number condition. Special attention was paid to effects of numerical set-up of LESs, such as differencing schemes and a wall function for calculating sub-grid scale stresses. The present simulations were based on a LES version with PIMPLEfoam of OpenFOAM, in which the option of RANS scheme was turn off with adding subgrid-scale diffusion estimated by the Smagorinsky model. Two kinds of differencing schemes and wall functions were used, i.e., one was a limited-linear and the other was a liner-upwind scheme with a low-Reynolds number type or a Spaliding type wall function. Effects of numerical set-up on time averaged values of these forces and the Strouhal number, which is a non-dimensional parameter for the frequency of waveform of these forces, were neglectable. On the other hand, the time-series and p.d.f.s of fluctuation components of drag and lift forces clearly showed the upwind scheme with a low Reynolds number type wall function yields attenuations of fluctuating forces. Contrary to these, the LESs by using a limited-linear scheme gave the good agreement of r.m.s. values of fluctuating these forces with previous studies based on DNSs, implying that LESs for examining dynamic behavior of drag and lift forces must require differencing schemes with small numerical diffusions.
