Fast water streams deflected by transverse walls

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On the flexural vibration of cylinders under axial loads:Numerical and experimental study

The flexural vibration of a homogeneous isotropic linearly elastic cylinder of any aspect ratio is analysed in this paper. Natural frequencies of a cylinder under uniformly distributed axial loads acting on its bases are calculated numerically by the Ritz method with terms of power series in the coordinate directions as approximating functions. The effect of axial loads on the flexural vibration cannot be described by applying infinitesimal strain theory, therefore, geometrically nonlinear strain–displacement relations with second-order terms are considered here. The natural frequencies of free–free, clamped–clamped, and sliding–sliding cylinders subjected to axial loads are calculated using the proposed three-dimensional Ritz approach and are compared with those obtained with the finite element method and the Bernoulli–Euler theory. Different experiments with cylinders axially compressed by a hydraulic press are carried out and the experimental results for the lowest flexural frequency are compared with the numerical results. An approach based on the Ritz formulation is proposed for the flexural vibration of a cylinder between the platens of the press with constraints varying with the intensity of the compression. The results show that for low compressions the cylinder behaves similarly to a sliding–sliding cylinder, whereas for high compressions the cylinder vibrates as a clamped–clamped one

Investigation of interference effects for a group of finite cylinders

[[abstract]]An experimental study of the interference effects between two and three cylinders of finite height immersed in a turbulent boundary layer at subcritical Reynolds numbers has been conducted in a boundary layer wind tunnel, utilizing a pneumatic averaging manifold system to measure the fluctuating force at various levels. Measurements of mean drag and lift force coefficients, mode-generalized RMS drag and lift force coefficients, and mode-generalized drag and lift force spectra, for a range of cylinder spacings, configurations, and various angles of attack, are presented. The interference levels observed were found to depend strongly on the spacing, angle of attack, and the arrangement of the cylinders with respect to each other. The investigation of these relationships for finite cylinders should prove insightful to those interested in such phenomena.[[notice]]補正完畢[[journaltype]]國外[[incitationindex]]SCI[[incitationindex]]E