Cavitation Due to Shock Pulses Reflected from the Sea Surface

Wentzell, R. A.; Scott, H D; Chapman, R. P.

doi:10.1121/1.1911762

Cited by 16 publications

(4 citation statements)

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“…Also, a fracture will appear once (2.10) holds. The fracture and the cavitation models are similar to those employed by other authors (e.g., [15,19]). …”

Section: Fracture and Cavitation Modelsmentioning

confidence: 96%

A Second-Order Godunov Method for Wave Problems in Coupled Solid–Water–Gas Systems

Tang

Sotiropoulos

1999

Journal of Computational Physics

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“…Also, a fracture will appear once (2.10) holds. The fracture and the cavitation models are similar to those employed by other authors (e.g., [15,19]). …”

Section: Fracture and Cavitation Modelsmentioning

confidence: 96%

A Second-Order Godunov Method for Wave Problems in Coupled Solid–Water–Gas Systems

Tang

Sotiropoulos

1999

Journal of Computational Physics

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“…There are, however, theoretical objections against this supposition, because it can be shown that the pressure wave can only be delayed but never be absorbed at the surface. For small explosions this delay has experimentally been verified by Wentzell, Scott & Chapman (1969).…”

Section: Calculation Of the Source Signalmentioning

confidence: 69%

Generation of Seismic Waves by Underwater Explosions

Wielandt

1975

Geophysical Journal International

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Siirnmar-yThis is a theoretical investigation of the seismic signal generated by underwater explosions. The explosion is described in terms of a ' volume source' that is characterized by the displaced volume as a function of time, where the shape and the pressure of the source need not be known. By solving the linear wave equation with boundary conditions representing a volume source at the sea bottom, a simple linear relation is derived between the source volume and the seismic far-field displacement. It is shown that this relation remains valid, as a good approximation, for explosive sources. In this way the volume of the explosion gas bubble may be taken as the source volume within the linear theory. It can be calculated numerically but is, in practice, inferred from the bubble period.The theory should apply to all sufficiently deep underwater explosions. Some questions remain when the explosion is so shallow that it produces cavitation at the surface. Nevertheless, for explosions near optimum depth, the theory predicts the amplitude spectrum and the absolute amplitude of the seismic signal well within the experimental scatter.

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“…Surface disturbances are also caused by the interaction of the oscillating bubble and its radiated pressure with the water-air interface if the bubble is in close vicinity to the free surface. In addition to the disturbance of the interface, cavitation below the interface can occur caused by the negative reflected pressure pulse (Wentzell et al, 1969). This could also lead to energy losses from the ghost reflection.…”

Section: Introductionmentioning

confidence: 99%

On low frequencies emitted by air guns at very shallow depths — An experimental study

Wehner

Landrø²,

Amundsen

2019

GEOPHYSICS

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In marine seismic acquisition, the enhancement of frequency amplitudes below 5 Hz is of special interest because it improves imaging of the subsurface. The frequency content of the air gun, the most commonly used marine seismic source, is mainly controlled by its depth and the volume. Although the depth dependency on frequencies greater than 5 Hz has been thoroughly investigated, for frequencies less than 5 Hz it is less understood. However, recent results suggest that sources fired very close to the sea surface might enhance these very low frequencies. Therefore, we conduct dedicated tank experiments to investigate the changes of the source signal for very shallow sources in more detail. A small-volume air gun is fired at different distances from the water-air interface, including depths for which the air bubble bursts directly into the surrounding air. The variations of the oscillating bubble and surface disturbances, which can cause changes of the reflected signal from the sea surface, are explored to determine whether an increased frequency signal below 5 Hz can be achieved from very shallow air guns. The results are compared with field measurements of a large-volume air gun fired close to the sea surface. The results reveal an increased signal for frequencies below 5 Hz of up to 10 and 20 dB for the tank and field experiments, respectively, for the source depth at which the air gun bubble bursts directly into the surrounding air. For large-volume air guns, an increased low-frequency signal might also be achieved for sources that are slightly deeper than this bursting depth. From these observations, new design considerations in the geometry of air-gun arrays in marine seismic acquisition are suggested.

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Cavitation Due to Shock Pulses Reflected from the Sea Surface

Cited by 16 publications

References 0 publications

A Second-Order Godunov Method for Wave Problems in Coupled Solid–Water–Gas Systems

A Second-Order Godunov Method for Wave Problems in Coupled Solid–Water–Gas Systems

Generation of Seismic Waves by Underwater Explosions

On low frequencies emitted by air guns at very shallow depths — An experimental study

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