2 edition of Oscillatory wave forces on a vertical circular cylinder including viscous effects found in the catalog.
Oscillatory wave forces on a vertical circular cylinder including viscous effects
Adam R. Black
by ocean Engineering Dept., Stevens Institute of Technology, Castle Point Station in Hoboken, N.J
Written in English
|Statement||by Adam R. Black.|
|Series||Report - Stevens Institute of Technology, Ocean Engineering Department -- SIT-OE-71-5.|
|The Physical Object|
|Pagination||viii, 22 p. :|
|Number of Pages||30|
A circular cylinder oscillating with sinusoidal motion in still water is a simple experimental model of circular structural members exposed to continuous wave motion. The accuracy of the numerical model is validated in this section. Validations included 1) oscillatory boundary-layer flows on a rough seabed; 2) fluid forces on a circular cylinder laid near a smooth-plane wall in oscillatory flows; and 3) fluid forces on a circular cylinder near a seabed in steady current.
Assessment of Viscous Damping via 3D-CFD Modelling of a Floating Wave Energy Device Majid A. Bhinder 1*, Aurélien Babarit 1#, Lionel Gentaz 1, Pierre Ferrant 1Laboratoire de Mécanique des Fluides - UMR CNRS n° Ecole Centrale de Nantes France. *[email protected] #[email protected] Abstract — The impact of the viscous and vortex forces in th e. The slow-drift motion of arrays of vertical cylinders By 0. J. in monochromatic waves is studied and an explicit solution is obtained for a vertical circular cylinder of infinite draught. This solution is extended for arrays of vertical the ‘fast’ oscillatory responses induced by linear wave effects and restored by.
Pipe lines and wall-proximity effects Wave impact loads 5 Wave forces on large bodies Introduction The case of linear diffraction Froude–Krylov force The case of a circular cylinder Higher-order wave diffraction and the force acting on a vertical cylinder . Otter A., “Damping Forces on a Circular Cylinder Oscillating in a Viscous Fluid, ” Applied Ocean Research, Vol. 12, 5. Otter A., “Forces on an Oscillating Cylinder and Related Fluid Flow Phenomena, ” Doctoral Thesis, University of Twente,
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The oscillatory viscous flow becomes unstable to axially periodic vortices above a critical Keulegan–Carpenter number K (K = U m T / D, U m = the maximum velocity in a cycle, T = the period of flow oscillation, and D = the diameter of the circular cylinder) for a given β (β = Re / K = D 2 / vT, Re = U m D / v, and v = the kinematic viscosity of fluid) as shown experimentally by Honji () Cited by: The diffraction of water waves by a vertical circular cylinder is considered in the regime where the wave amplitude A and cylinder radius a are of the same order, and both are small compared to the wavelength.
The wave slope is small, and a conventional linear analysis applies in the outer domain far from the cylinder. Significant nonlinear effectsCited by: Self-Excited Oscillations of Vertical and Horizontal Cylinders in Presence of a Free-Surface Y., Asano, T., & Nagai, F. () Hydrodynamic forces on a circular cylinder placed in wave-current co-existing fields.
Memo Faculty of () Force on a circular cylinder in viscous oscillatory flow at low Keulegan-Carpenter numbers. Journal of Author: D. Rockwell, M. Ozgoren, N. Saelim. The second-order wave force is analysed for diffraction of monochromatic water waves by a vertical cylinder.
The force is evaluated directly from pressure integration over the cylinder, and the second-order potential is derived by Weber transformation Cited by: The flow around a circular cylinder in waves exerts a resultant in-line force (drag and inertia) and cross-flow force (lift) on the cylinder; a thorough account on the topic is provided in Justesen ().
Cylinder diameter and surface roughness both influence the resultant force as well as the velocity, period and amplitude of the wave : Thor Ugelvig Petersen, Xerxes Mandviwalla, Erik Damgaard Christensen, Niels Jacob Tarp-Johansen, Fin.
To solve the diffraction of water waves by a bottom-fixed vertical circular cylinder, a numerical analysis by the boundary element method is developed by using linear potential theory.
A numerical analysis by boundary element method is based on Green’s theorem and introduced to an integral equation for the fluid velocity potential around the vertical circular cylinder.
However, in Sansome () it was noted that in some cases, oscillatory forces were reduced by amounts greater than predicted by superposition theory, and that friction effects possibly accounted for the difference.
force that increases with increase in displacement from mean position. Types of oscillatory motion: It is of two types such as linear oscillation and circular oscillation. Example of linear oscillation: 1. Oscillation of mass spring system.
Oscillation of fluid column in a U-tube. Oscillation of floating cylinder. The stochastic properties of the drag force maxima on a circular cylinder subjected to nonlinear random waves are investigated. Unseparated laminar high Reynolds number flow is considered. Forces on cylinders in viscous oscillatory flow at low Keulegan-Carpenter numbers - Volume - P.
Bearman, M. Downie, J. Graham, E. Obasaju. A complete theory to obtain semianalytical solutions of the wave drift damping for a circular cylinder freely oscillating in waves is developed.
The wave drift damping can be significantly increased by heave and pitch motions. Effects of the draft of the cylinder and effects of the water depth are shown. toward a vertical cylinder whose cross section is described by the equation r= R+"f() with "˝1. The function f() describes the deviation of the shape of the cylinder from the circular one, f() = 0 corresponds to the circular cylinder with radius R.
The problem of wave scattering by a nearly circular cylinder was formulated in . Cobbin et al. () modeled a timedependent, attached, oscillatory, turbulent boundary-layer flow over a smooth circular cylinder, with the ratio of fluid particle amplitude to diameter cylinder.
Høgedal, MExperimental Study of Wave Forces on Vertical Circular Cylinders in Long and Short Crested Sea. Series paper, no. 6, Hydraulics & Coastal Engineering Laboratory, Department of Civil Engineering, Aalborg University, Aalborg.
The Proceedings: Fifth International Conference on Numerical Ship Hydrodynamics () Chapter: Simulations of Forces Acting on a Cylinder in Oscillatory Flow by Direct Calculation of the Navier-Stokes Equations.
Wave forces on vertical cylinders are due to both viscous and inertial effects. The problem appears to be considerably simplified when the forces are predominantly inertial.
In general, the inertial forces predominate as cylinder diameter and wter depth increase. A column-stabilized floating ocean platform presents such a case. The general arrangement. viscous effects are assumed to be very small.
The horizontal and vertical components of wave forces acting on the submerged cylinder are measured with the multi-component load cell. It may be noted that the down-wave and downward forces are considered positive as shown in Fig. The forces are made. The cylinder was rigidly fixed on to the carriage and positioned at the centre of the tank width as shown conceptually in Fig.
1, using a specially designed frame that avoids any vibrations and movements during the wave the tests, two depths of submergence were chosen, h = and m, thus making d/h ratios= andrespectively, where d is the water depth and h is the. Li et al. () and Li et al. () experimentally investigated the interactions between multidirectional focused wave and a bottom-mounted vertical cylinder and demonstrated the effects of wave parameters on the wave run-up and wave force.
This paper presents the results of an experimental study on the steady-streaming flow and the resulting scour process around a large vertical circular cylinder exposed to a progressive wave. The differences of the wave force coefficients between a horizontal cylinder in waves and in planar oscillatory flow are shown.
The effects of a current on the force coefficients are examined.Koterayama studied the wave force coefficients for a circular cylinder moving with a constant speed in regular waves; the Keulegan–Carpenter numbers for the wave motion ranged from to and the reduced velocity defined by the constant speed and the wave period ranged from 0 to For a circular cylinder oscillating sinusoidally with a very low frequency in regular waves and a cylinder.Oscillating cylinder in viscous ﬂuid He described a three-dimensional instability of the ﬂow appearing in the form of an oscillatory cell pattern in the boundary layer of the oscillating cylinder.
The cylinder motion was given by 1 2 d(t)= 1 2 d0 sin(2πft), with 1 2 d0 the amplitude and f = 1/T the frequency. In his original work Honji.