Abstract：To alleviate the requirement of mesh resolution in the near-wall region, an immersed boundary method, called the local domain-free discretization (DFD) method, is extended to large eddy simulation (LES) of turbulent flows. The discrete form of partial differential equations at an interior node may involve some nodes outside the solution domain. The flow variables at these exterior dependent nodes are evaluated via linear extrapolation along the direction normal to the wall. A wall model based on the turbulence boundary layer equations is introduced. The wall shear stress yielded by the wall model and the no-penetration condition are enforced at the immersed boundary to evaluate the velocity components at an exterior dependent node. For turbulence closure, a dynamic subgrid scale (SGS) model is adopted and the Lagrangian averaging procedure is used to compute the model coefficient. The SGS eddy viscosity at an exterior dependent node is set to be equal to that at the outer layer. Numerical experiments of backward-facing step flow on relatively coarse meshes have been conducted to verify the ability of the present LES-DFD method. The predicted results agree well with the published experimental or numerical data.
徐振东, 段宇轩, 徐华松, 杨帆, 李铁. 当地DFD方法向LES湍流模拟推广的研究[J]. 空天防御, 2022, 5(3): 93-98.
XU Zhendong, DUAN Yuxuan, XU Huasong, YANG Fan, LI tie. Extension of the Local Domain-Free Discretization Method to Large Eddy Simulation of Turbulent Flows. Air & Space Defense, 2022, 5(3): 93-98.
