Reconfiguration and drag reduction of flexible beam with point buoyancy in oscillatory flow

Abstract

Flexible structures with point buoyancy widely exist in nature and engineering. Under the action of oscillating flow, it usually has a large geometric nonlinear dynamic response. However, the dynamic response and drag reduction of flexible structures with point buoyancy have not been studied. Therefore, the numerical method in this paper investigates the dynamic response and drag reduction of point buoyant flexible structures under oscillatory flow. Firstly, complex spatial curvilinear coordinates establish the dynamic partial differential equations of flexible structures with point buoyancy. Then, the implicit finite-difference time-domain method is used to discretize the partial differential equation in space and time to form an algebraic equation. Finally, the dynamic response and drag reduction of flexible structures under non-buoyancy, uniform buoyancy, and point buoyancy are numerically analyzed. The results show that with the increase of Cauchy number C_Y, the deformation of the flexible structure becomes larger and larger, and a local bending point appears. The dimensionless vibration frequency numbers explain the occurrence of local bending points. Unlike no buoyancy, uniform buoyancy and point buoyancy make the flexible structure smaller and more symmetrical. Uniform buoyancy and point buoyancy can increase the Reconfiguration number R. The greater the buoyancy and buoyancy position, the greater the Reconfiguration number R. The load on the flexible structure under oscillating flow is still less than that on the rigid structure. The Vogel exponent is calculated by fitting the Reconfiguration number R. The drag reduction is directly proportional to the Vogel exponent v, that is, the greater the Vogel exponent v, the greater the drag reduction. When the Cauchy number C_Y is large, the Vogel exponent v of uniform buoyancy and point buoyancy is smaller than that of non-buoyancy. The greater the point buoyancy and buoyancy position, the smaller the deformation of the flexible structure, the greater the Reconfiguration number R, and the greater the Vogel exponent v. When the buoyancy position is small, the influence of point buoyancy on the flexible structure can be ignored.