Simulation of Turbulent Flow over an Airfoil Using Hybrid RANS-LES Approach

Due to the immense computational effort required, the direct numerical simulation (DNS) or even Large Eddy Simulation (LES) of fluid flow will not be a practical alternative even for the next four or five decades. On the other hand, Using RANS in near-wall regions would significantly mitigate the mesh resolution requirement. In order to alleviate problem possible solution is to blend large-eddy simulation with another technique which must be able to provide relevant low-frequency solutions at a much lower cost. In this paper we have implemented Hybrid RANS-LES approach which combines URANS version of eddy viscosity transport model of Spalart-Allmaras (S-A) and a filtered version of that model. The case is an A-airfoil of 12.3 deg angle of attack at Reynolds number of 2.1×106 for which the approach is demonstrated to yield valid solutions toONERA wind tunnel data. This was performed on structured grid, whose density is shown to provide a reasonably accurate trailing-edge flow. Hybrid RANSLES approach can be considered as a more practical alternative to LES simulations of the flow around high- Re high-lift airfoils.

کلیدواژه ها:

CFD ، Turbulence ، Hybrid RANS-LES