Wave-induced seabed response in a cross-anisotropic seabed in front of a breakwater: An analytical solution

1998 ◽  
Vol 25 (1) ◽  
pp. 49-67 ◽  
Author(s):  
Dong-Sheng Jeng
Keyword(s):  
Analytical Solution ◽  
Wave Induced

Impact of fluid saturation on the reflection coefficient of a poroelastic layer

Geophysics ◽  
2011 ◽  
Vol 76 (2) ◽  
pp. N1-N12 ◽  
Author(s):  
Beatriz Quintal ◽  
Stefan M. Schmalholz ◽  
Yuri Y. Podladchikov
Keyword(s):  
Fluid Flow ◽  
Reflection Coefficient ◽  
Analytical Solution ◽  
Quality Factor ◽  
Velocity Dispersion ◽  
Normal Incidence ◽  
Sand Layer ◽  
Partially Saturated ◽  
Fluid Saturation ◽  
Wave Induced

The impact of changes in saturation on the frequency-dependent reflection coefficient of a partially saturated layer was studied. Seismic attenuation and velocity dispersion in partially saturated (i.e., patchy saturated) poroelastic media were accounted for by using the analytical solution of the 1D White’s model for wave-induced fluid flow. White’s solution was applied in combination with an analytical solution for the normal-incidence reflection coefficient of an attenuating layer embedded in an elastic or attenuating background medium to investigate the effects of attenuation, velocity dispersion, and tuning on the reflection coefficient. Approximations for the frequency-dependent quality factor, its minimum value, and the frequency at which the minimum value of the quality factor occurs were derived. The approximations are valid for any two alternating sets of petrophysical parameters. An approximation for the normal-incidence reflection coefficient of an attenuating thin (compared to the wavelength) layer was also derived. This approximation gives insight into the influence of contrasts in acoustic impedance and/or attenuation on the reflectivity of a thin layer. Laboratory data for reflections from a water-saturated sand layer and from a dry sand layer were further fit with petrophysical parameters for unconsolidated sand partially saturated with water and air. The results showed that wave-induced fluid flow can explain low-frequency reflection anomalies, which are related to fluid saturation and can be observed in seismic field data. The results further indicate that reflection coefficients of partially saturated layers (e.g., hydrocarbon reservoirs) can vary significantly with frequency, especially at low seismic frequencies where partial saturation may often cause high attenuation.

On the Accuracy of an Analytical Solution to Model Wave-Induced Loads on an Underwater Vehicle in Real-Time

2020 ◽  
pp. 1-18
Author(s):  
Joseph Klamo ◽  
Travis M. Turner ◽  
Colin Y. Cool ◽  
Kathryn I. Yeager ◽  
Young W. Kwon
Keyword(s):  
Analytical Solution ◽  
The Body ◽  
Body Of Revolution ◽  
Unmanned Underwater Vehicles ◽  
Submerged Body ◽  
Pitch Moment ◽  
Theoretical Assumptions ◽  
Disturbance Model ◽  
Wave Induced ◽  
Large Parameter Space

Abstract The accuracy of an existing analytical solution for modeling the linear, first-order wave- induced loads on a fully submerged body is investigated. The accuracy is assessed for the situation where the underlying theoretical assumptions are met and the sensitivity of the accuracy to these assumptions is also explored. The accuracy was quantified by comparing the analytical solutions to experimental measurements from a tow tank with wave generation capability. The assessment showed that when all the assumptions are met, the heave and surge forces are predicted quite accurately but the pitch moment is over predicted. The results also showed that the deeply submerged assumption is met as long as the body does not cause a disruption of the passing wave on the free surface. The slenderness and end face curvature assumptions are also quite relaxed and the curvature assumption only affects the pitch moment accuracy. The most stringent assumption appears to be the body-of revolution assumption which can cause all three loads to be predicted poorly. The analytical solution appears to be accurate over a large parameter space and could be incorporated as a wave disturbance model into a virtual environment used to develop control and autonomy of unmanned underwater vehicles.

An analytical solution for wave-induced seabed response in a multi-layered poro-elastic seabed

2011 ◽  
Vol 38 (1) ◽  
pp. 119-129 ◽  
Author(s):  
Xiang-Lian Zhou ◽  
Bin Xu ◽  
Jian-Hua Wang ◽  
Yao-Liang Li
Keyword(s):  
Analytical Solution ◽  
Wave Induced

scholarly journals An Analytical Solution of Flow and Progressive Wave-Induced Residual Pore Water Pressure in Seabed

2015 ◽  
Vol 31 (7) ◽  
pp. 13-28
Author(s):  
Kwang-Ho Lee ◽  
Dong-Wook Kim ◽  
Gi-Chun Kang ◽  
Do-Sam Kim ◽  
Tae-Hyung Kim
Keyword(s):  
Analytical Solution ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Progressive Wave ◽  
Wave Induced

scholarly journals Three-Dimensional Wave-Induced Dynamic Response in Anisotropic Poroelastic Seabed

Water ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1465 ◽  
Author(s):  
Cheng-Jung Hsu ◽  
Ching Hung
Keyword(s):  
Analytical Solution ◽  
Effective Stress ◽  
Three Dimensional ◽  
Wave Direction ◽  
Anisotropic Permeability ◽  
Present Solution ◽  
Transverse Isotropic ◽  
Vertical Effective Stress ◽  
Wave Induced ◽  
Dimensional Wave

This paper presents a novel analytical solution, which is developed for investigating three-dimensional wave-induced seabed responses for anisotropic permeability. The analytical solution is based on the assumption of the poroelastic and the u − p dynamic form, which considers the inertia force of the soil skeleton. In this paper, the problem is regarded as an eigenvalue problem through a first-order ordinary differential equation in matrix form. The problematic eigenvector involved in the solution is dealt with using numerical computation, and a process is proposed to implement the present solution for the desired dynamic response. A verification, which is compared with two existing solutions, demonstrates an agreement with the present solution. The results show that the amplitude profile of seabed response for a shorter wave period varies significantly. A comparison between the anisotropic and transverse isotropic, as well as isotropic permeabilities reveals that the error of vertical effective stress on the seabed bottom can reach 74 . 8 % for the isotropic case. For anisotropic permeability, when the wave direction is parallel to the higher horizontal permeability direction, the amplitude profiles of pore pressure and vertical effective stress exhibit the greatest dissipation and increment, respectively. For transverse isotropic permeability, the vertical effective stress is independent of the wave direction, which results in the two horizontal effective stresses on the seabed bottom being identical to each other and independent of the wave direction. Our comprehensive analysis provides insight into the effect of anisotropic permeability on different wave periods and wave directions.

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