RANS-RSM-based, eddy-resolving modelling of complex turbulent flows

  • Jakirlic, Suad (Technical University of Darmstadt, Germany)

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The present work deals with the scale-resolving simulation of complex turbulent flow configurations. The complexity of flow refers to a variety of differently structured phenomena relevant to aircraft aerodynamics, internal combustion engines and their corresponding cooling channels, two-phase flow in bubble columns, physiological flows in the human aorta, flows around blunt bodies, and complex duct and tube configurations characteristic of various industrial applications. Comparative evaluation of the results with various reference databases from relevant experimental and numerical simulation studies shows the correctly predicted instantaneous character of the flow as well as its averaged pattern [1-7]. The anisotropic turbulence residing in unresolved motion is described by a RANS-based (Reynolds-averaged Navier-Stokes) eddy-resolving closure that accounts for the dynamics of the entire subscale stress tensor. The eddy-resolving capability of the model is enabled by the introduction of an additional production term into the length-scale determining transport equation. Its functional dependence on the second derivative of the underlying velocity field is motivated by the Scale-adaptive Simulation (SAS) strategy by Menter and Egorov (2010, FTaC 85:113-138). This RANS-based Reynolds stress model, sensitized to the turbulent fluctuations, brings important advantages. This primarily concerns the grid spacing-independent model formulation, which is particularly effective for arbitrarily complex grid cell arrangements and accordingly solves the problem of the otherwise unclear determination of the characteristic filter size/length in LES-relevant simulation methods correspondingly well.