Temporal Discretization Investigation of the Unsteady Loading on an Infinitely Long Cylinder in High Reynolds Numbers Using DES

Abstract

Abstract The flow around circular cylinders has been extensively investigated over the past decades, both numerically and experimentally, due to its importance in offshore applications. However, the phenomenon of vortex shedding remains not completely understood at supercritical and postcritical regimes due to difficulties in representing the nature of separated flows past bluff bodies at such high Reynolds numbers. This work thus presents a numerical investigation of the flow field and its forces on a circular cylinder at supercritical and postcritical Reynolds regimes using Computational Fluid Dynamics (CFD), more specifically the Finite Volume Method (FVM) implemented in the Open-FOAM software. The flow past a fixed circular cylinder of aspect ratio equal to 2 and periodic boundary conditions at its ends is assessed for Re = 1 × 106, 3.6 × 106, and 1 × 107. We employed the hybrid detached eddy simulation (DES) along with Menter’s k-ω SST model as a turbulence closure model, and analyzed the loads acting on the cylinder and other flow features, such as Strouhal frequency, at each regime. A temporal discretization analysis was carried out for the Reynolds regime of 107, whereby three different Courant-Friedrichs-Lewy (CFL) numbers were tested, namely CFL equal to 0.25, 0.5, and 1. The capability of each CFD simulation in capturing the physics of the system is assessed by comparing it with results found in the literature for similar cases, in terms of lift and drag coefficients, and Strouhal frequency. The numerical investigations presented satisfactory results for all cases; however, a considerable increase in the computational demand was noticed for higher Reynolds numbers and lower CFL numbers, CFL = 0.25 and 0.5.