A new hybrid turbulence modelling strategy for industrial CFD

This paper presents a new strategy for turbulence model employment with emphasis on the modelʹs applicability for industrial computational fluid dynamics (CFD). In the hybrid modelling strategy proposed here, the Reynolds stress and mean rate of strain tensors are coupled via Boussinesqʹs formula as in the standard k-(epsilon)model. However, the turbulent kinetic energy is calculated as the sum of the normal Reynolds-stress components, representing the solutions of the appropriate transport equations. The equations governing the Reynolds-stress tensor and dissipation rate have been solved in the framework of a ʹbackgroundʹ second-moment closure model. Furthermore, the structure parameter C-(mu) has been re-calculated from a newly proposed functional dependency ...rather than kept constant. This new definition of C-(mu) has been assessed by using direct numerical simulation (DNS) results of several generic flow configurations featuring different phenomena such as separation, reattachment and rotation. Comparisons show a large departure of C-(mu) from the commonly used value of 0.09. The model proposed is computationally validated in a number of well-proven fluid flow benchmarks, e.g. backward-facing step, 180° turn-around duct, rotating pipe, impinging jet and three-dimensional (3D) Ahmed body. The obtained results confirm that the present hybrid model delivers a robust solution procedure while preserving most of the physical advantages of the Reynolds-stress model over simple k-(epsilon)models. A low Reynolds number version of the hybrid model is also proposed and discussed