scholarly journals Resurrecting dead-water phenomenon

2011 ◽  
Vol 18 (2) ◽  
pp. 193-208 ◽  
Author(s):  
M. J. Mercier ◽  
R. Vasseur ◽  
T. Dauxois
Keyword(s):  
Internal Waves ◽  
Large Amplitude ◽  
Experimental Studies ◽  
Nonlinear Effects ◽  
Stratified Fluid ◽  
Nonlinear Internal Waves ◽  
Induced Drag ◽  
Wave Induced ◽  
Dead Water ◽  
Peculiar Phenomenon

Abstract. We revisit experimental studies performed by Ekman on dead-water (Ekman, 1904) using modern techniques in order to present new insights on this peculiar phenomenon. We extend its description to more general situations such as a three-layer fluid or a linearly stratified fluid in presence of a pycnocline, showing the robustness of dead-water phenomenon. We observe large amplitude nonlinear internal waves which are coupled to the boat dynamics, and we emphasize that the modeling of the wave-induced drag requires more analysis, taking into account nonlinear effects. Dedicated to Fridtjöf Nansen born 150 yr ago (10 October 1861).

Numerical study of internal wave–wave interactions in a stratified fluid

2000 ◽  
Vol 415 ◽  
pp. 65-87 ◽  
Author(s):  
A. JAVAM ◽  
J. IMBERGER ◽  
S. W. ARMFIELD
Keyword(s):  
Internal Wave ◽  
Internal Waves ◽  
Numerical Study ◽  
Experimental Studies ◽  
Interaction Mechanism ◽  
Stratified Fluid ◽  
Interaction Region ◽  
Staggered Grid ◽  
Open Boundary ◽  
Wave Interactions

A finite volume method is used to study the generation, propagation and interaction of internal waves in a linearly stratified fluid. The internal waves were generated using single and multiple momentum sources. The full unsteady equations of motion were solved using a SIMPLE scheme on a non-staggered grid. An open boundary, based on the Sommerfield radiation condition, allowed waves to propagate through the computational boundaries with minimum reflection and distortion. For the case of a single momentum source, the effects of viscosity and nonlinearity on the generation and propagation of internal waves were investigated.Internal wave–wave interactions between two wave rays were studied using two momentum sources. The rays generated travelled out from the sources and intersected in interaction regions where nonlinear interactions caused the waves to break. When two rays had identical properties but opposite horizontal phase velocities (symmetric interaction), the interactions were not described by a triad interaction mechanism. Instead, energy was transferred to smaller wavelengths and, a few periods later, to standing evanescent modes in multiples of the primary frequency (greater than the ambient buoyancy frequencies) in the interaction region. The accumulation of the energy caused by these trapped modes within the interaction region resulted in the overturning of the density field. When the two rays had different properties (apart from the multiples of the forcing frequencies) the divisions of the forcing frequencies as well as the combination of the different frequencies were observed within the interaction region.The model was validated by comparing the results with those from experimental studies. Further, the energy balance was conserved and the dissipation of energy was shown to be related to the degree of nonlinear interaction.

scholarly journals Huge internal waves in the vicinity of the Spitsbergen Island (Barents Sea)

2011 ◽  
Vol 11 (3) ◽  
pp. 981-986 ◽  
Author(s):  
O. E. Kurkina ◽  
T. G. Talipova
Keyword(s):  
Numerical Model ◽  
Cross Section ◽  
Internal Waves ◽  
Barents Sea ◽  
Stratified Fluid ◽  
High Latitudes ◽  
Barotropic Tide ◽  
Nonlinear Internal Waves ◽  
Total Height ◽  
The Barents Sea

Abstract. The generation of huge amplitude internal waves by the barotropic tide in the Barents Sea at high latitudes is examined using the numerical model of the Euler 2-D equations for incompressible stratified fluid. The area considered is located between the Spitsbergen (Svalbard) Island and the Franz-Victoria Trough with a cross-section of 350 km length. There are two underwater hills about 100–150 m high on the background depth of about 300 m. It is shown that intensive nonlinear internal waves with amplitudes up to 50 m and lengths of about 6–12 km are generated in this zone. The total height of such waves is huge and they must be considered as a significant factor of the environment in this basin.

Observations of Large-Amplitude Mode-2 Nonlinear Internal Waves on the Australian North West Shelf

2019 ◽  
Vol 49 (1) ◽  
pp. 309-328 ◽  
Author(s):  
Matthew D. Rayson ◽  
Nicole L. Jones ◽  
Gregory N. Ivey
Keyword(s):  
Internal Waves ◽  
Large Amplitude ◽  
Transition Period ◽  
Local Mode ◽  
Driving Mechanism ◽  
Length Scale ◽  
North West ◽  
Nonlinear Internal Waves ◽  
Mode 2 ◽  
Amplitude Mode

AbstractLarge-amplitude mode-2 nonlinear internal waves were observed in 250-m-deep water on the Australian North West shelf. Wave amplitudes were derived from temperature measurements using three through-the-water-column moorings spaced 600 m apart in a triangular configuration. The moorings were deployed for 2 months during the transition period between the tropical monsoon and the dry season. The site had a 25–30-m-amplitude mode-1 internal tide that essentially followed the spring–neap tidal cycle. Regular mode-2 nonlinear wave trains with amplitudes exceeding 25 m, with the largest event exceeding 50 m, were also observed at the site. Overturning was observed during several mode-2 events, and the relatively high wave Froude number and steepness (0.15) suggested kinematic (convective) instability was likely to be the driving mechanism. The presence of the mode-2 waves was not correlated with the tidal forcing but rather occurred when the nonlinear steepening length scale was smaller than the distance from the generation region to the observation site. This steepening length scale is inversely proportional to the nonlinear parameter in the Korteweg–de Vries equation, and it varied by at least one order of magnitude under the evolving background thermal stratification over the observation period. Despite the complexity of the internal waves in the region, the nonlinear steepening length was shown to be a reliable indicator for the formation of large-amplitude mode-2 waves and the rarer occurrence of mode-1 large-amplitude waves. A local mode-2 generation mechanism caused by a beam interacting with a pycnocline is demonstrated using a fully nonlinear numerical solution.

Seafloor Pressure Measurements of Nonlinear Internal Waves

2008 ◽  
Vol 38 (2) ◽  
pp. 481-491 ◽  
Author(s):  
J. N. Moum ◽  
J. D. Nash
Keyword(s):  
Hydrostatic Pressure ◽  
Internal Waves ◽  
Opposite Sign ◽  
Surface Displacement ◽  
Pressure Measurements ◽  
Nonlinear Internal Waves ◽  
Nonhydrostatic Pressure ◽  
Seafloor Pressure ◽  
Wave Induced ◽  
Pressure Perturbations

Abstract Highly resolved pressure measurements on the seafloor over New Jersey’s continental shelf reveal the pressure signature of nonlinear internal waves of depression as negative pressure perturbations. The sign of the perturbation is determined by the dominance of the internal hydrostatic pressure (p0Wh) due to isopycnal displacement over the contributions of external hydrostatic pressure (ρ0gηH; ηH is surface displacement) and nonhydrostatic pressure (p0nh), each of opposite sign to p0Wh. This measurement represents experimental confirmation of the wave-induced pressure signal inferred in a previous study by Moum and Smyth.

Nonlinear internal waves in a stratified fluid in a closed basin

1978 ◽  
Vol 1 (2) ◽  
pp. 136-146
Author(s):  
M. Falcioni ◽  
A. Sutera ◽  
F. Zirilli
Keyword(s):  
Internal Waves ◽  
Stratified Fluid ◽  
Closed Basin ◽  
Nonlinear Internal Waves

scholarly journals Shoaling of large-amplitude nonlinear internal waves at Dongsha Atoll in the northern South China Sea

2012 ◽  
Vol 37 ◽  
pp. 1-7 ◽  
Author(s):  
Ke-Hsien Fu ◽  
Yu-Huai Wang ◽  
Louis St. Laurent ◽  
Harper Simmons ◽  
Dong-Ping Wang
Keyword(s):  
South China Sea ◽  
Internal Waves ◽  
South China ◽  
Large Amplitude ◽  
Northern South China Sea ◽  
Nonlinear Internal Waves ◽  
China Sea ◽  
Dongsha Atoll

scholarly journals The modified Korteweg - de Vries equation in the theory of large - amplitude internal waves

1997 ◽  
Vol 4 (4) ◽  
pp. 237-250 ◽  
Author(s):  
R. Grimshaw ◽  
E. Pelinovsky ◽  
T. Talipova
Keyword(s):  
Solitary Wave ◽  
Internal Waves ◽  
Solitary Waves ◽  
Large Amplitude ◽  
Nonlinear Term ◽  
Vries Equation ◽  
Nonlinear Effects ◽  
Wave Generation ◽  
Density Stratification ◽  
De Vries

Abstract. The propagation of large- amplitude internal waves in the ocean is studied here for the case when the nonlinear effects are of cubic order, leading to the modified Korteweg - de Vries equation. The coefficients of this equation are calculated analytically for several models of the density stratification. It is shown that the coefficient of the cubic nonlinear term may have either sign (previously only cases of a negative cubic nonlinearity were known). Cubic nonlinear effects are more important for the high modes of the internal waves. The nonlinear evolution of long periodic (sine) waves is simulated for a three-layer model of the density stratification. The sign of the cubic nonlinear term influences the character of the solitary wave generation. It is shown that the solitary waves of both polarities can appear for either sign of the cubic nonlinear term; if it is positive the solitary waves have a zero pedestal, and if it is negative the solitary waves are generated on the crest and the trough of the long wave. The case of a localised impulsive initial disturbance is also simulated. Here, if the cubic nonlinear term is negative, there is no solitary wave generation at large times, but if it is positive solitary waves appear as the asymptotic solution of the nonlinear wave evolution.

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