Experimental evidence of internal solitary wave-induced global instability in shallow water benthic boundary layers

2008 ◽  
Vol 20 (6) ◽  
pp. 066603 ◽  
Author(s):  
M. Carr ◽  
P. A. Davies ◽  
P. Shivaram
Keyword(s):  
Solitary Wave ◽  
Experimental Evidence ◽  
Shallow Water ◽  
Boundary Layers ◽  
Internal Solitary Wave ◽  
Global Instability ◽  
Wave Induced

Reduction of internal-solitary-wave-induced forces on a circular cylinder with a splitter plate

2018 ◽  
Vol 83 ◽  
pp. 119-132 ◽  
Author(s):  
Ling-ling Wang ◽  
Jin Xu ◽  
Yin Wang ◽  
Gang Wei ◽  
Chang Lin ◽  
...  
Keyword(s):  
Circular Cylinder ◽  
Solitary Wave ◽  
Splitter Plate ◽  
Internal Solitary Wave ◽  
Wave Induced

scholarly journals Numerical Investigation of Solitary Internal Wave-Induced Global Instability in Shallow Water Benthic Boundary Layers

2006 ◽  
Vol 36 (5) ◽  
pp. 784-812 ◽  
Author(s):  
Peter J. Diamessis ◽  
Larry G. Redekopp
Keyword(s):  
Boundary Layer ◽  
Internal Wave ◽  
Shallow Water ◽  
Water Column ◽  
Separation Bubble ◽  
Vertical Direction ◽  
Finite Difference Schemes ◽  
Global Instability ◽  
Solitary Internal Wave ◽  
Wave Induced

Abstract The time-dependent boundary layer induced by a weakly nonlinear solitary internal wave in shallow water is examined through direct numerical simulation. Waves of depression and elevation are both considered. The mean density field corresponds to that typical of the coastal ocean and lakes where the lower fraction of the water column is subject to the stabilizing effect of a diffuse stratification. Sufficient resolution of the “inviscid” dynamics of the boundary layer is ensured through use of a Legendre spectral multidomain discretization scheme in the vertical direction. At higher Reynolds numbers, where the simulations become underresolved, because of restrictions in available computational resources, spectral accuracy and numerical stability at the scales of physical interest are preserved through use of a penalty scheme in the vertical and explicit spectral filtering. Thus, a highly accurate description of the qualitative dynamics of the wave-induced global instability is possible and finescale physical mechanisms critical to the appearance of this instability are not smeared out by the high artificial dissipation inherent in lower-order finite-difference schemes. Results indicate that, for a wave amplitude exceeding a critical value, the global instability occurs in regions near the bottom boundary where the wave induces an adverse pressure gradient. The structure of the associated separation bubble is modified through the establishment of coherent and synchronous dynamics, characterized by elevated levels of bottom shear stress and a periodic shedding of coherent vortex structures. Although details of the vortex shedding depend on the particular wave forcing involved, these vortical structures always ascend high into the water column. All findings suggest that this global instability is a potent mechanism for benthic turbulence, mixing, and possible sediment resuspension in shallow waters, presumably even more intense than the nominal turbulent boundary layer.

Observations of fine structure changes in shoaling internal solitary waves based on seismic oceanography method

2021 ◽  
Author(s):  
Haibin Song ◽  
Yi Gong ◽  
Yongxian Guan ◽  
Wenhao Fan ◽  
Yunyan Kuang
Keyword(s):  
Fine Structure ◽  
Solitary Wave ◽  
Phase Velocity ◽  
Shallow Water ◽  
Solitary Waves ◽  
Internal Solitary Wave ◽  
Internal Solitary Waves ◽  
Seismic Events ◽  
Velocity Amplitude ◽  
Seismic Oceanography

<p>In the study of shoaling internal solitary waves, the observation and research on the internal fine structure and the effect of the topography are still insufficient. We try to make up for such insufficiency by seismic oceanography method. A first-mode depression internal solitary wave was observed propagating on the continental slope in the northeast South China Sea near Dongsha Atoll. We used common offset gathers (COGs) to obtain a series of images of this internal solitary wave that evolved over time, and studied the changes in internal fine structure by analyzing the seismic events in COG migrated sections. We found that the seismic events were broken during the shoaling, which was caused by the instability induced by internal solitary wave. We picked six events which represent six waveform and analyzed their evolution. It was found that the change in shape of waveform at different depths is different. The waveform in deep water deforms before that in shallow water, and the waveform in shallow water deforms to a greater degree. In addition, we also counted four parameters of phase velocity, amplitude, wavelength, and slopes of front and rear during the shoaling. The results show that the phase velocity and amplitude of waveform in shallow water increases, the wavelength decreases, and the slope of rear gradually becomes larger than that of the front. We have compared the observed changes with previous study made by numerical simulation.</p>

scholarly journals Retrieval of Internal Solitary Wave Amplitude in Shallow Water by Tandem Spaceborne SAR

2019 ◽  
Vol 11 (14) ◽  
pp. 1706
Author(s):  
Jia ◽  
Liang ◽  
Li ◽  
Fan
Keyword(s):  
Solitary Wave ◽  
Shallow Water ◽  
Layer Thickness ◽  
Kdv Equation ◽  
World Ocean ◽  
Internal Solitary Wave ◽  
Accurate Estimation ◽  
Sar Images ◽  
De Vries

The accurate estimation of the upper layer thickness in a two-layer ocean is a crucial step in the retrieval of internal solitary wave (ISW) amplitude from synthetic aperture radar (SAR) data. In this paper, we present a method to derive the upper layer thickness and the consequent ISW amplitude by combining two consecutive SAR images with the extended Korteweg-de Vries (eKdV) equation. An ISW case observed twice by the Chinese C-band SAR GaoFen-3 (GF-3) and the German X-band SAR TerraSAR-X (TS-X) with a temporal interval of approximately 11 minutes in shallow water to the southeast of Hainan Island in the northwestern South China Sea was used to demonstrate the applicability of the method. Using the in situ measurements of temperature and salinity near the observed ISW, the proposed method yielded an ISW amplitude of −4.52 m, in close proximity to −5.66 ± 1.24 m derived by applying the classic Korteweg–de Vries (KdV) equation based on the continuously stratified theory. Moreover, the climatological dataset of the World Ocean Atlas 2013 (WOA13) was also used with the proposed method in the Hainan case, and the results showed that the method can still provide a reasonable estimate of ISW amplitude in shallow water even when in situ oceanic stratification measurements are absent. The application of our method to derive the ISW amplitude from consecutive SAR images seems highly promising with the increasing emergence of tandem satellites in orbits.

scholarly journals Observations of Internal Structure Changes in Shoaling Internal Solitary Waves Based on Seismic Oceanography Method

2021 ◽  
Vol 8 ◽  
Author(s):  
Haibin Song ◽  
Yi Gong ◽  
Shengxiong Yang ◽  
Yongxian Guan
Keyword(s):  
Fine Structure ◽  
Solitary Wave ◽  
Phase Velocity ◽  
Shallow Water ◽  
Solitary Waves ◽  
Deep Water ◽  
Internal Solitary Wave ◽  
Internal Solitary Waves ◽  
Structure Changes ◽  
Different Depths

High spatial resolution and deep detection depths of seismic reflection surveying are conducive to studying the fine structure of the internal solitary wave. However, seismic images are instantaneous, which are not conducive to observing kinematic processes of the internal solitary waves. We improved the scheme of seismic data processing and used common-offset gathers to continuously image the same location. In this way, we can observe internal fine structure changes during the movement of the internal solitary waves, especially the part in contact with the seafloor. We observed a first-mode depression internal solitary wave on the continental slope near the Dongsha Atoll of the South China Sea and short-term shoaling processes of the internal solitary wave by using our improved method. We found that the change in shape of waveform varies at different depths. We separately analyzed the evolution of the six waveforms at different depths. The results showed that the waveform in deep water deforms before that in shallow water and the waveform in shallow water deforms to a greater degree. We measured four parameters of the six waveforms during the shoaling including phase velocity, amplitude, wavelength, and slopes of leading and trailing edge. The phase velocity and amplitudes of waveforms in shallow water increase, the wavelengths decrease, and the slopes of trailing edge gradually become larger than that of the leading edge, while the amplitudes of the deep water waveforms do not change significantly and the phase velocities decrease. Our results are consistent with previous studies made by numerical simulations, which suggest the effectiveness of the new processing scheme. This improved scheme cannot only study the internal solitary waves shoaling, but also has great potential in the study of other ocean dynamics.

Internal solitary wave-induced flow over a corrugated bed

2010 ◽  
Vol 60 (4) ◽  
pp. 1007-1025 ◽  
Author(s):  
Magda Carr ◽  
Marek Stastna ◽  
Peter A. Davies
Keyword(s):  
Solitary Wave ◽  
Internal Solitary Wave ◽  
Induced Flow ◽  
Wave Induced

Observation of dynamic fine structure in ocean using pre-stack seismic data

2020 ◽  
Author(s):  
Yi Gong ◽  
Haibin Song ◽  
Wenhao Fan ◽  
Yongxian Guan ◽  
Kun Zhang
Keyword(s):  
Fine Structure ◽  
Solitary Wave ◽  
Flow Velocity ◽  
Seismic Data ◽  
Internal Solitary Wave ◽  
Reflection Seismic ◽  
Water Region ◽  
The Common ◽  
Induced Velocity ◽  
Wave Induced

<p>We propose a method for observing the dynamic thermohaline fine structure using pre-stack seismic data, and combine it with PIV(Particle-Image-Velocimetry) technology to obtain a series of vertical two-dimensional flow velocity sections.<br>Because of the redundancy of the multi-channel reflection seismic data, the reflection seismic structure at the same location can be observed multiple times from pre-stack seismic data. First, we extract the common-midpoint gathers (CMPs) from the multi-channel reflection seismic data. Then extract the common-offset gathers (COGs) from CMPs. Finally, a seismic processing sequence, such as noise attenuation, normal move out (NMO), velocity analysis and migration, is applied for imaging the reflection structure in COG sections. These COG sections with different offsets are the images of the thermohaline fine structure of seawater at different times. We apply this method to study a typical internal solitary wave in the Dongsha plateau of the South China Sea. We find that the waveform of the internal solitary wave(ISW) in shallow water region does not change much during propagation, but the front becomes flatter and the rear becomes steeper in deep water region, so there is a ISW shoaling change vertically. <br>We apply the PIV technique to the COG pre-stack migrated sections and calculate the flow velocity sections of the internal solitary wave. To verify the correctness of the flow velocity sections, we compare it with the theoretical flow velocity section calculated from the KdV equation. It is found that the two sections are consistent in flow directions, and the PIV result shows the structure of wave induced velocity well. In the PIV calculation results, the average value of the velocity in the horizontal direction is 1.7 m/s, and in the vertical direction is 0.3 m/s. This result is larger than the theory, especially the horizontal velocity. We speculate that the horizontal velocity contains not only the wave induced velocity component of the internal solitary wave but also the phase velocity component.<br>In summary, we use pre-stack seismic data to observe changes in the thermohaline fine structure during the propagation of internal solitary waves, and find that the waveforms of internal solitary waves vary differently at different depths. We use the PIV technique to calculate the flow velocity section of the internal solitary wave and compare it with the theoretical results. We find that our method is feasible to describe the flow velocity qualitatively, but it needs further improvement in quantitative description. This method has great potential in studying the dynamic evolution of mesoscale or submesoscale ocean processes.</p>

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