scholarly journals The evolution of mode-2 internal solitary waves modulated by background shear currents

2018 ◽  
Author(s):  
Peiwen Zhang ◽  
Zhenhua Xu ◽  
Qun Li ◽  
Baoshu Yin ◽  
Yijun Hou ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Solitary Wave ◽  
Wave Packet ◽  
Solitary Waves ◽  
Transfer Process ◽  
Energy Transfer Process ◽  
Average Rate ◽  
Internal Solitary Waves ◽  
Mode 2 ◽  
Background Shear

Abstract. The evolution process of mode-2 internal solitary waves (ISWs) modulated by the background shear currents was investigated numerically. The forward-propagating long wave, amplitude-modulated wave packet were generated during the early stage of modulation, where the amplitude-modulated wave packet were suggested playing an important role in the energy transfer process, and then the oscillating tail was generated and followed the solitary wave. Five different cases were introduced to assess the sensitivity of the energy transfer process to the Δ, which defined as a dimensionless distance between the centers of pycnocline and shear current. The forward-propagating long waves were found robust to the Δ, but the oscillating tail and amplitude-modulated wave packet decreased in amplitude with increasing Δ. The highest energy loss rate was observed when Δ = 0. In the first 30 periods, ~ 36 % of the total energy lost at an average rate of 9 W m−1, it would deplete the energy of the solitary wave in ~ 4.5 h, corresponding to a propagation distance of ~ 5 km, which is consistent with the hypothesis of Shroyer et al. (2010), who speculated that the mode-2 ISWs are short-lived in the presence of shear currents.

scholarly journals The evolution of mode-2 internal solitary waves modulated by background shear currents

2018 ◽  
Vol 25 (2) ◽  
pp. 441-455 ◽  
Author(s):  
Peiwen Zhang ◽  
Zhenhua Xu ◽  
Qun Li ◽  
Baoshu Yin ◽  
Yijun Hou ◽  
...  
Keyword(s):  
Wave Packet ◽  
Shear Layer ◽  
Solitary Waves ◽  
Average Rate ◽  
Propagation Distance ◽  
Internal Solitary Waves ◽  
Long Wave ◽  
Shear Current ◽  
Mode 2 ◽  
Background Shear

Abstract. The evolution of mode-2 internal solitary waves (ISWs) modulated by background shear currents was investigated numerically. The mode-2 ISW was generated by the “lock-release” method, and the background shear current was initialized after the mode-2 ISW became stable. Five sets of experiments were conducted to assess the sensitivity of the modulation process to the direction, polarity, magnitude, shear layer thickness and offset extent of the background shear current. Three distinctly different shear-induced waves were identified as a forward-propagating long wave, oscillating tail and amplitude-modulated wave packet in the presence of a shear current. The amplitudes of the forward-propagating long wave and the amplitude-modulated wave packet are proportional to the magnitude of the shear but inversely proportional to the thickness of the shear layer, as well as the energy loss of the mode-2 ISW during modulation. The oscillating tail and amplitude-modulated wave packet show symmetric variation when the background shear current is offset upward or downward, while the forward-propagating long wave was insensitive to it. For comparison, one control experiment was configured according to the observations of Shroyer et al. (2010); in the first 30 periods, ∼ 36 % of total energy was lost at an average rate of 9 W m−1 in the presence of the shear current; it would deplete the energy of initial mode-2 ISWs in ∼ 4.5 h, corresponding to a propagation distance of ∼ 5 km, which is consistent with in situ data.

scholarly journals Combined Effect of Rotation and Topography on Shoaling Oceanic Internal Solitary Waves

2014 ◽  
Vol 44 (4) ◽  
pp. 1116-1132 ◽  
Author(s):  
Roger Grimshaw ◽  
Chuncheng Guo ◽  
Karl Helfrich ◽  
Vasiliy Vlasenko
Keyword(s):  
Solitary Wave ◽  
Wave Packet ◽  
Numerical Simulations ◽  
Solitary Waves ◽  
Combined Effect ◽  
Internal Solitary Wave ◽  
Internal Solitary Waves ◽  
De Vries ◽  
Ostrovsky Equation ◽  
Variable Topography

Abstract Internal solitary waves commonly observed in the coastal ocean are often modeled by a nonlinear evolution equation of the Korteweg–de Vries type. Because these waves often propagate for long distances over several inertial periods, the effect of Earth’s background rotation is potentially significant. The relevant extension of the Kortweg–de Vries is then the Ostrovsky equation, which for internal waves does not support a steady solitary wave solution. Recent studies using a combination of asymptotic theory, numerical simulations, and laboratory experiments have shown that the long time effect of rotation is the destruction of the initial internal solitary wave by the radiation of small-amplitude inertia–gravity waves, and the eventual emergence of a coherent, steadily propagating, nonlinear wave packet. However, in the ocean, internal solitary waves are often propagating over variable topography, and this alone can cause quite dramatic deformation and transformation of an internal solitary wave. Hence, the combined effects of background rotation and variable topography are examined. Then the Ostrovsky equation is replaced by a variable coefficient Ostrovsky equation whose coefficients depend explicitly on the spatial coordinate. Some numerical simulations of this equation, together with analogous simulations using the Massachusetts Institute of Technology General Circulation Model (MITgcm), for a certain cross section of the South China Sea are presented. These demonstrate that the combined effect of shoaling and rotation is to induce a secondary trailing wave packet, induced by enhanced radiation from the leading wave.

Internal Solitary Waves with shear: beyond DJL theory

2020 ◽  
Author(s):  
Marek Stastna ◽  
Aaron Coutino ◽  
Ryan Walter
Keyword(s):  
Solitary Wave ◽  
Solitary Waves ◽  
Wave Train ◽  
Theoretical Description ◽  
Internal Solitary Wave ◽  
Shear Instability ◽  
Internal Solitary Waves ◽  
Wave Trains ◽  
Set Up ◽  
Background Shear

<p>While background shear is ubiquitous in the natural environment, the vast majority of theoretical and numerical studies of internal solitary waves do not include a background shear.  Walter et al 2016, Continental Shelf Research reported on measurements in Monterey Bay in which large amplitude internal solitary wave trains were observed but corresponding waves could not be computed from DJL theory due to the strength of the background shear.  In this talk I will revisit this issue using a classical stratified adjustment set up.  For the case of an exponential, surface trapped background current I will demonstrate that internal solitary wave trains with and without trapped cores coexist with a substantial region dominated by stratified shear instability and/or Rayleigh Taylor instability.  I will then demonstrate the type of internal wave train that results in cases when the the variational formulation of the DJL equation fails to converge. I will speculate on implications for theoretical description of such waves and for more realistic simulations in the coastal ocean.</p>

Heat, quantum mechanics and information

2015 ◽  
Vol 10 (2) ◽  
pp. 2692-2695
Author(s):  
Bhekuzulu Khumalo
Keyword(s):  
Information Theory ◽  
Quantum Mechanics ◽  
Energy Transfer ◽  
Transfer Process ◽  
Energy Transfer Process ◽  
Process Information ◽  
Double Slit Experiment ◽  
Slit Experiment ◽  
Double Slit

Heat has often been described as part of the energy transfer process. Information theory says everything is information. If everything is information then what type of information is heat, this question can be settled by the double slit experiment, but we must know what we are looking for. 

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