A Dual-mesh Hybrid Les/rans Framework with Implicit Consistency

INTRODUCTION The high computational cost of Large Eddy Simulation (LES) for wall-bounded flows at high Reynolds numbers still is a major hurdle for applications to practical flows in industry and nature [3]. To overcome this difficulty, various hybrid LES/RANS methods have been proposed, of which the most widely used one is Detached Eddy Simulation (DES). Recently, Xiao and Jenny [4] developed a novel hybrid LES/RANS framework, where LES and RANS simulations are conducted simultaneously on the entire domain on separate meshes. Relaxation forces are applied on the respective equations to ensure consistency between the two solutions. Numerical simulations were conducted based on this algorithm; the results demonstrate that the proposed method leads to satisfactory results on relatively coarse meshes, which is promising for industrial flow simulations [4,5]. In this work, to combine the consistency feature of the original formulation from the hybrid LES/RANS framework [4] and the forcing strategy used by other hybrid methods, we propose an implicitly consistent formulation coupling with a modified forcing strategy. In this modified formulation the turbulent stresses are directly corrected, which allows for a direct use of the RANS Reynolds stresses in the LES. This direct approach is advantageous especially when a sophisticated RANS model is employed.