Impact of body inclination on the flow past a rotating cylinder

The rotation applied to a circular cylinder, rigidly mounted in a current perpendicular to its axis, can result in the suppression of vortex shedding and of the associated force fluctuations. It also causes the emergence of a myriad of two- and three-dimensional flow regimes. The present paper explores numerically the impact of a deviation from the normal incidence configuration, by considering a rotating cylinder inclined in the current. The Reynolds number based on the body diameter and the magnitude of the current velocity component normal to its axis (U-perpendicular to) is set to 100. The range of values of the rotation rate (ratio between body surface velocity and U-perpendicular to, alpha is an element of [0, 5.5]) encompasses the two unsteady flow regions and three-dimensional transition identified at normal incidence. The inclination angle (theta) refers to the angle between the current direction and the plane perpendicular to the cylinder axis. A low inclination angle (theta is an element of{15 degrees, 30 degrees}), i.e. slight deviation from normal incidence (theta = 0 degrees), has a limited influence on the global evolution of the flow with alpha, which can be predicted via the independence principle (IP), based on U-perpendicular to only. This highlights the robustness of prior observations made for theta = 0 degrees. Some effects of the axial flow are, however, uncovered in the high-alpha range; in particular, the single-sided vortex shedding is replaced by an irregular streamwise-oriented structure. In contrast, a large inclination angle (theta = 75 degrees) leads to a major reorganization of flow evolution scenario over the entire alpha range, with the disappearance of all steady regimes, the occurrence of structures reflecting the pronounced asymmetry of the configuration (oblique shedding, strongly slanted vorticity tongues) and a dramatic departure of fluid forces from the IP prediction.

Automated summary

The study investigates the effect of a rotating cylinder inclined in a current on flow dynamics, finding that a low inclination angle has limited impact on the global flow evolution, while a high inclination angle leads to a major reorganization of the flow scenario. This includes irregular streamwise structures, pronounced asymmetry, and a significant departure of fluid forces from predictions.