Fully consistent CFD methods for incompressible flow computations

The Science of Making Torque from Wind 2014

Kolmogorov, D.K.^1 ; Shen, W.Z.^1 ; Sørensen, N.N.^2 ; Sørensen, J.N.^1

Technical University of Denmark, Nils Koppels Alle, Building 403, 2800, Kgs. Lyngby, Denmark^1

Technical University of Denmark, Building 114, Frederiksborgvej 399, 4000, Roskilde, Denmark^2

关键词: Collocated grids;    Convergence rates;    Interpolation method;    Momentum interpolation methods;    Pressure-velocity coupling;    SIMPLEC algorithm;    Turbulent flow computation;    Wind turbine wakes;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/524/1/012128/pdf
DOI  :  10.1088/1742-6596/524/1/012128

来源: IOP

【 摘 要 】

Nowadays collocated grid based CFD methods are one of the most efficient tools for computations of the flows past wind turbines. To ensure the robustness of the methods they require special attention to the well-known problem of pressure-velocity coupling. Many commercial codes to ensure the pressure-velocity coupling on collocated grids use the so-called momentum interpolation method of Rhie and Chow [1]. As known, the method and some of its widely spread modifications result in solutions, which are dependent of time step at convergence. In this paper the magnitude of the dependence is shown to contribute about 0.5% into the total error in a typical turbulent flow computation. Nevertheless if coarse grids are used, the standard interpolation methods result in much higher non-consistent behavior. To overcome the problem, a recently developed interpolation method, which is independent of time step, is used. It is shown that in comparison to other time step independent method, the method may enhance the convergence rate of the SIMPLEC algorithm up to 25 %. The method is verified using turbulent flow computations around a NACA 64618 airfoil and the roll-up of a shear layer, which may appear in wind turbine wake.