Radiation and diffraction by a submerged sphere advancing in water waves of finite depth

1995 ◽  
Vol 448 (1932) ◽  
pp. 29-54 ◽  
Keyword(s):  
Water Waves ◽  
Finite Depth ◽  
Multipole Expansion ◽  
The Body ◽  
Field Equations ◽  
Damping Coefficients ◽  
Submerged Sphere ◽  
Added Masses ◽  
Exciting Forces ◽  
Depth Water

A submerged sphere advancing in a regular finite depth water wave at constant forward speed is analysed by linearized velocity potential. The solution is ob­tained by the multipole expansion extended from that developed for zero speed. Numerical results are obtained for wave-making resistance and lift, added masses, damping coefficients and exciting forces. Far field equations are also derived for calculating damping coefficients and exciting forces. They are used to check the results obtained from integrating pressure over the body surface. Excellent agree­ment is found.

Radiation and diffraction of water waves by a submerged sphere at forward speed

1988 ◽  
Vol 417 (1853) ◽  
pp. 433-461 ◽  
Keyword(s):  
Water Waves ◽  
Velocity Potential ◽  
Surface Condition ◽  
Wave Resistance ◽  
The Body ◽  
Legendre Functions ◽  
Forward Speed ◽  
Submerged Sphere ◽  
Exciting Forces ◽  
Similar Equation

A submerged sphere advancing in regular deep-water waves at constant forward speed is analysed by linearized potential theory. A distribution of sources over the surface of the sphere is expanded into a series of Legendre functions, by extension of the method used by Farell ( J . Ship Res . 17, 1 (1973)) in analysing the wave resistance on a submerged spheroid. The equations governing the velocity potential are satisfied by use of the appropriate Green function and by choosing the coefficients in the series of Legendre functions such that the body surface condition is satisfied. Numerical results are obtained for the wave resistance, hydrodynamic coefficients and exciting forces on the sphere. Some theoretical aspects of a body advancing in waves are also discussed. The far-field equation of Newman ( J . Ship Res . 5, 44 (1961)) for calculation of the damping coefficients is extended, and a similar equation for the exciting forces is derived.

Theory of Short Wave Excitation

1986 ◽  
Vol 30 (03) ◽  
pp. 147-152
Author(s):  
Yong Kwun Chung
Keyword(s):  
Incident Wave ◽  
Characteristic Length ◽  
Finite Depth ◽  
Short Wave ◽  
The Body ◽  
Wave Number ◽  
Floating Body ◽  
Wave Excitation ◽  
Exciting Forces ◽  
Wave Exciting Forces

When the wavelength of the incident wave is short, the total surface potential on a floating body is found to be 2∅ i & O (m-l∅ i) on the lit surface and O (m-l∅ j) on the shadow surface where ~b i is the potential of the incident wave and m the wave number in water of finite depth. The present approximation for wave exciting forces and moments is reasonably good up to X/L ∅ 1 where h is the wavelength and L the characteristic length of the body.

Radiation of waves by a cylinder submerged in water with ice floe or polynya

2015 ◽  
Vol 784 ◽  
pp. 373-395 ◽  
Author(s):  
Izolda V. Sturova
Keyword(s):  
Elastic Plate ◽  
Diffraction Problem ◽  
Open Water ◽  
Finite Depth ◽  
The Body ◽  
Elastic Plates ◽  
Radiation Problem ◽  
Radiation Load ◽  
Body Contour ◽  
Damping Coefficients

The problems of radiation (sway, heave and roll) of surface and flexural-gravity waves by a submerged cylinder are investigated for two configurations, concerning; (i) a freely floating finite elastic plate modelling an ice floe, and (ii) two semi-infinite elastic plates separated by a region of open water (polynya). The fluid of finite depth is assumed to be inviscid, incompressible and homogeneous. The linear two-dimensional problems are formulated within the framework of potential-flow theory. The method of mass sources distributed along the body contour is applied. The corresponding Green’s function is obtained by using matched eigenfunction expansions. The radiation load (added mass and damping coefficients) and the amplitudes of vertical displacements of the free surface and elastic plates are calculated. Reciprocity relations which demonstrate both symmetry of the radiation load coefficients and the relation of damping coefficients with the far-field form of the radiation potentials are found. It is shown that wave motion essentially depends on the position of the submerged body relative to the elastic plate edges. The results of solving the radiation problem are compared with the solution of the diffraction problem. It is noted that resonant frequencies in the radiation problem correlate with those frequencies at which the reflection coefficient in the diffraction problem has a local minimum.

Hydrodynamic forces on a submerged cylinder advancing in water waves of finite depth

1991 ◽  
Vol 224 ◽  
pp. 645-659 ◽  
Author(s):  
G. X. Wu
Keyword(s):  
Water Waves ◽  
Outer Region ◽  
Finite Element Approximation ◽  
Finite Depth ◽  
Horizontal Cylinder ◽  
Hydrodynamic Forces ◽  
Boundary Integral ◽  
Circular Cylinders ◽  
Element Approximation ◽  
Field Equations

The hydrodynamic problem of a submerged horizontal cylinder advancing in regular water waves of finite depth at constant forward speed is analysed by the linearized velocity potential theory. The Green function is first derived. Far-field equations for calculating damping coefficients and exciting forces are obtained. The numerical method used combines a finite-element approximation of the potential in a region surrounding the cylinder with a boundary-integral-equation representation of the outer region. Numerical results for the hydrodynamic forces on submerged circular cylinders and elliptical cylinders are provided.

Scattering of water waves by inclined thin plate submerged in finite-depth water

2001 ◽  
Vol 71 (12) ◽  
pp. 827-840 ◽  
Author(s):  
Ch. Midya ◽  
M. Kanoria ◽  
B. N. Mandal
Keyword(s):  
Thin Plate ◽  
Water Waves ◽  
Finite Depth ◽  
Depth Water

Hydrodynamic Forces on a Submerged Sphere Undergoing Large Amplitude Motion

1994 ◽  
Vol 38 (04) ◽  
pp. 272-277
Author(s):  
G. X. Wu
Keyword(s):  
Boundary Condition ◽  
Free Surface ◽  
Large Amplitude ◽  
Multipole Expansion ◽  
The Body ◽  
Surface Boundary ◽  
Free Surface Boundary Condition ◽  
Submerged Sphere ◽  
Instantaneous Position ◽  
Surface Boundary Condition

The hydrodynamic problem of a sphere submerged below a free surface and undergoing large amplitude oscillation is investigated based on the velocity potential theory. The body surface boundary condition is satisfied on its instantaneous position while the free-surface boundary condition is linearized. The solution is obtained by writing the potential in terms of the multipole expansion.

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