A review of hybrid RANS-LES methods for turbulent flows: Concepts and applications

Abstract The hybridization of Reynolds-averaged Navier-Stokes (RANS) and large eddy simulation (LES) methods is seen to be the most promising way to efficiently deal with separated turbulent flow simulations relevant to aerospace and wind energy applications. Characteristic conceptual features of popular hybrid RANS-LES and their applications to hill-type and airfoil flow including flow separation are described. Conceptual questions on existing hybrid RANS-LES are pointed out and ways to overcome these problems are presented. Further analyses show that corresponding novel hybrid RANS-LES methods generalize and improve existing methods. The discussions reveal, in particular, the great value of physical and mathematical realizability constraints for the substantial improvement of simulation methods.