Scrutinizing Conventional and Eddy-Resolving Unsteady RANS Approaches in Computing the Flow and Aeroacoustics Past a Tandem Cylinder

Abstract

A conventional differential, near-wall Reynolds stress model (RSM) [2] and its eddy-resolving version, sensitized appropriately to account for turbulence unsteadiness (denoted as instability-sensitive RSM - IS-RSM [3]), are applied within the Unsteady RANS computational framework to the flow past an in-line tandem-cylinder arrangement. The scale-supplying equation governing the homogeneous part of the inverse turbulent time scale $\omega _h$ ($\omega _h = \varepsilon _h/k)$, both model schemes are based on, includes an additional production term in the IS-RSM formulation. This model term, originating from Menter and Egorov’s Scale-Adaptive Simulation (SAS) concept [11], enables the model’s eddy-resolving capability. The complex unsteady vortex shedding process featuring the tandem cylinder flow at the Reynolds number of ${1.66 \times 10^{5}}$ and cylinder in-between spacing of 3.7D is correctly, qualitatively and quantitatively, captured by the present IS-RSM model, in contrast to the conventional URANS approach. The superiority of the IS-RSM model is reflected furthermore in predicting the acoustic pressure by applying an indirect approach in line with Curle’s acoustic analogy [1].