Experimental and numerical studies of the flow over a circular cylinder at Reynolds number 3900

Abstract

This work contributes to the study of flow over a circular cylinder at Reynolds number Re= 3900. Although this classical flow is widely documented in the literature, especially for this precise Reynolds number that leads to a subcritical flow regime, there is no consensus about the turbulence statistics immediately just behind the obstacle. Here, the flow is investigated both numerically with large eddy simulation and experimentally with hot-wire anemometry and particle image velocimetry. The numerical simulation is performed using high-order schemes and a specific immersed boundary method. The present study focuses on turbulence statistics and power spectra in the near wake up to ten diameters. Statistical estimation is shown to need large integration times increasing the computational cost and leading to an uncertainty of about 10% for most flow characteristics considered in this study. The present numerical and experimental results are found to be in good agreement with previous large eddy simulation data. Contrary to this, the present results show differences compared to the experimental data found in the literature, the differences being larger than the estimated uncertainty range. Therefore, previous numerical-experimental controversy for this flow seems to be reduced with the data presented in this article.

Low-frequency unsteadiness in the vortex formation region of a circular cylinder

“…Norberg 6 in his work, suggested that there is a change in the wake configuration at Re = 5000. This transition was later confirmed by Prasad and 12 Williamson, 41 while Norberg 39 attributed this change to a transition between a high-and low-quality vortex shedding mode. The results here presented suggest that at Re = 3900 both modes coexist and the wake is oscillating between them at a very low-frequency, and as has been shown this is the cause of the large scattering in the experimental and numerical results observed up until now.…”

“…For comparison, the solutions for each mode are plotted together with the experimental results from Parnaudeau et al 12 and the numerical results of Case I from Ma et al 11 (finer grid and larger span-wise domain). These reference solutions have been selected as both of them point out contradictory wake statistics due to their differences in the recirculation zone (L r /D = 1.51 and L r /D = 1.12, respectively).…”

Nonequilibrium scalings of turbulent wakes

“…[8]. The modeling of the square plate is performed by an immersed boundary method, following a procedure proposed by [12]. Inflow and outflow boundary conditions are assumed in the streamwise direction, with a uniform fluid velocity U ∞ without turbulence as inflow condition and a 1D convection equation as outflow condition.…”

Numerical analysis of the immersed boundary method applied to the flow around a forced oscillating cylinder

“…Regarding the validation, studies as [4,5,6,7] using Incompact3d, presented both qualitatively and quantitatively results for conventional and complex flow geometries around fixed obstacles. According such studies, the code is a very attractive tool for solving flows in the context of Direct Numerical Simulations (DNS).…”

“…The principle of direct forcing is to preserve the no-slip boundary condition avoiding discontinuities in the first derivative at the cylinder surface [4].…”