Numerical Experiments on the Flow Past a Circular Cylinder at Sub-CriticalReynolds Number

摘要

The performance of the dynamic subgrid-scale eddy-viscosity model and thesuitability of high-order accurate, upwind-biased numerical methods for large eddy simulations of complex flows are investigated in the case of the turbulent wake behind a circular cylinder at Reynolds number 3,900, based on freestream velocity and cylinder diameter. The numerical method consists of high-order upwind-biased finite difference techniques applied to the compressible Navier-Stokes equations written in generalized coordinates. Integration in time is done using a fully implicit, second-order accurate iterative technique. The results of three fifth-order accurate simulations performed on identical grids with the least-squares version of the dynamic model, the fixed-coefficient Smagorinsky model, and with no subgrid-scale model are compared in the first 10 diameters of the wake. The impact of three-dimensionality is also examined via two and three-dimensional calculations without a subgrid-scale model. The effect of numerical dissipation is investigated by comparing two simulations using upwind-biased schemes, the first being fifth-order, and the second seventh-order accurate. It is found that the near-wake is highly three-dimensional at this Reynolds number. It contains pairs of counter-rotating streamwise vortices, the effect of which cannot be reproduced in two-dimensional calculations. Three-dimensional computations are essential for predicting flow statistics of engineering interest. (AN).