2023 年 38 巻 p. 109-116
This study focuses on the flow field around a rotating cylinder and describes the effect of the rotation of the cylinder on the velocity distribution as part of the clarification of the hydrodynamic forces acting on a rotating cylinder in flow. A water tank experiment was conducted to measure the velocity distribution around a rotating cylinder. The measurement conditions were roughly divided into two groups: the side where the flow is decelerating and the side where the flow is increasing due to rotation.
On the side where the flow is slowed down by the rotation of the cylinder, the Reynolds stress increases due to the effect of the cylinder rotation, and the apparent viscosity increases. This makes it more difficult for the fluid to flow, leading to an overall decrease in the velocity distribution. On the side where the flow increases due to the rotation of the cylinder, the flow from the decelerating side is added, leading to an increase in the overall velocity distribution. In addition, a layer of highly turbulent flow due to the effect of cylinder rotation is formed near the surface of the cylinder, and flow from the decelerating side does not flow into the inside of this layer. As a result, the flow velocity distribution is consistent with the linear superposition of the flow velocity distribution around a rotating cylinder in a uniform flow and a stationary fluid.