HARBOUR RESONANCE UNDER IMPACT OF POWERFUL TSUNAMI

Shentong Lu; Jiin-Jen Lee; Xiuying Xing

doi:10.9753/icce.v34.currents.12

An Experimental Study of Harbour Resonance Phenomena

Coastal Engineering 1988 ◽

10.1061/9780872626874.019 ◽

1989 ◽

Author(s):

F. M. Martinez ◽

V. S. Naverac

Keyword(s):

Experimental Study ◽

Resonance Phenomena ◽

Harbour Resonance

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MODEL HARBOUR SEICHING COMPARED TO PROTOTYPE DATA

Coastal Engineering Proceedings ◽

10.9753/icce.v19.57 ◽

1984 ◽

Vol 1 (19) ◽

pp. 57

Author(s):

W.A.M. Botes ◽

K.S. Russell ◽

P. Huizinga

Keyword(s):

South African ◽

Nuclear Power ◽

Cooling Water ◽

Long Waves ◽

Power Station ◽

The West ◽

Pressure System ◽

Long Wave ◽

Low Pressure System ◽

Harbour Resonance

Since 1978 a finite-difference numerical model based on that developed by Leendertse and adapted for resonance studies (Russell and Huizinga, 1978) has been applied to investigate harbour resonance in Table Bay Harbour and several other South African ports. During April 1981 three long-wave recorders were installed in the cooling water intake basin of the Koeberg Nuclear Power Station to determine the occurrence and magnitude of the long waves and to measure the corresponding response of the basin. Koeberg is situated on the west coast of South Africa, 30 km north of Cape Town and is exposed to the approaching cyclonic weather systems which experience has shown to be associated with the occurrence of long waves. An example of an approaching low pressure system with the location of Koeberg is shown in Figure 1.

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CORRECT REPRODUCTION OF GROUP-INDUCED LONG WAVES

Coastal Engineering Proceedings ◽

10.9753/icce.v17.47 ◽

1980 ◽

Vol 1 (17) ◽

pp. 47

Author(s):

N.E. Ottesen Hansen ◽

Stig E. Sand ◽

H. Lundgren ◽

Torben Sorensen ◽

H. Gravesen

Keyword(s):

Second Order ◽

Long Waves ◽

Wave Problem ◽

Wave Groups ◽

Storm Waves ◽

Slow Drift ◽

Short Period ◽

Harbour Resonance ◽

The Waves ◽

Wave Phenomena

In nature short period storm waves generate longer waves with periods corresponding to the wave group periods. The long waves are generally referred to as the wave set-down of water level. The set-down term is of second order in the height of the short waves. With first order reproduction of natural storm waves in the laboratory, the setdown bound to the wave groups is not reproduced. As a result, various free waves are generated, propagate towards the model and reflect from the boundaries. These so-called parasitic waves cause an exaggeration of long wave phenomena, such as harbour resonance and slow drift oscillations of moored ships. The parasitic waves can be eliminated by means of compensating free waves imposed on the system by second-order paddle motion reproducing the natural set-down. The control signal for this motion has been calculated and checked by testing. The agreement between calculated and measured results is found to be good. Further, an alternative method for reducing the parasitic wave problem is presented. Utilizing the shoaling properties of the various waves, the influence of parasitic waves can be diminished by generating the waves in somewhat deeper water before they propagate into the shallower model area.

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Harbour resonance problems using finite elements

Advances in Water Resources ◽

10.1016/0309-1708(78)90004-0 ◽

1978 ◽

Vol 1 (4) ◽

pp. 205-211 ◽

Cited By ~ 2

Author(s):

S. Walker ◽

C.A. Brebbia

Keyword(s):

Finite Elements ◽

Harbour Resonance

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Harbour excitations by incident wave groups

Journal of Fluid Mechanics ◽

10.1017/s0022112090000866 ◽

1990 ◽

Vol 217 ◽

pp. 595-613 ◽

Cited By ~ 39

Author(s):

Jiang-Kang Wu ◽

Philip L.-F. Liu

Keyword(s):

Incident Wave ◽

Multiple Scales ◽

Low Frequency ◽

Second Order ◽

Long Waves ◽

Wave Groups ◽

Order Of Magnitude ◽

Harbour Resonance ◽

Analytical Expressions ◽

Multiple Scales Perturbation Method

By using the multiple-scales perturbation method, analytical solutions are obtained for the second-order low-frequency oscillations inside a rectangular harbour excited by incident wave groups. The water depth is a constant. The width of the harbour entrance is of the same order of magnitude as the wavelength of incident carrier (short) waves, but small in comparison with the wavelength of the wave envelope. Because of the modulations in the wave envelope, a second-order long wave is locked in with the wave envelope and propagates with the speed of the group velocity. Outside the harbour, locked long waves also exist in the reflected wave groups, but not in the radiated wave groups. Inside the harbour, the analytical expressions for the locked long waves are obtained. Owing to the discontinuity of the locked long waves across the harbour mouth, second-order free long waves are generated. The free long waves propagate with a speed of (gh)½ inside and outside the harbour. The free long waves inside the harbour may be resonated in a low-frequency range which is relevant to the harbour resonance.

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Harbour resonance due to set-down beneath wave groups

Journal of Fluid Mechanics ◽

10.1017/s0022112077000044 ◽

1977 ◽

Vol 79 (1) ◽

pp. 71-92 ◽

Cited By ~ 82

Author(s):

E. C. Bowers

Keyword(s):

Group Velocity ◽

Wave System ◽

Primary Wave ◽

Natural Oscillations ◽

Natural Period ◽

Wave Groups ◽

Long Period ◽

Natural Modes ◽

Long Wave ◽

Harbour Resonance

Natural modes of water oscillation inside harbours are known to occur with periods of the order of minutes. It seems likely that these oscillations are excited by water fluctuations of similar period outside the harbour and an often quoted cause of such fluctuations is the phenomenon of surf beats. These are thought to be long waves which are reflected back out to sea when a primary wave system breaks upon a beach. In this paper it is shown theoretically that the natural oscillations of a harbour can be excited directly, without breaking of the primary wave system, by set-down beneath wave groups, which is a long-period disturbance travelling towards the shore line at the group velocity. This theory is in agreement with model experimental results which show that, when the group period is close to a natural period of the harbour, resonance will occur with the set-down behaving as if it were a real long wave.

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