Comparisons of Methods for Numerical Internal Wave Simulation in Long-Range Acoustical Propagation

2016 ◽  
pp. 19-25
Author(s):  
Rex K. Andrew
Keyword(s):  
Internal Wave ◽  
Long Range ◽  
Wave Simulation

scholarly journals A long‐range acoustic experiment with sampling in the internal wave fluctuation band

1988 ◽  
Vol 84 (S1) ◽  
pp. S91-S91
Author(s):  
Timothy F. Duda ◽  
Stanley M. Flatté ◽  
Harry A. DeFerrari ◽  
Hien B. Nguyen
Keyword(s):  
Internal Wave ◽  
Long Range

Internal wave effects on long‐range ocean acoustic tomography

1995 ◽  
Vol 97 (5) ◽  
pp. 3235-3235
Author(s):  
M. A. Wolfson ◽  
J. L. Spiesberger ◽  
F. D. Tappert
Keyword(s):  
Internal Wave ◽  
Long Range ◽  
Acoustic Tomography ◽  
Wave Effects ◽  
Ocean Acoustic Tomography

scholarly journals Entropy rate defined by internal wave scattering in long-range propagation

2015 ◽  
Vol 138 (3) ◽  
pp. 1353-1364 ◽  
Author(s):  
Andrey K Morozov ◽  
John A. Colosi
Keyword(s):  
Internal Wave ◽  
Long Range ◽  
Wave Scattering ◽  
Entropy Rate

Internal wave simulation for different angles and shapes of continental shelf

2014 ◽  
Author(s):  
Himansu K. Pradhan ◽  
A. D. Rao ◽  
K. K. G. Reddy ◽  
S. Mohanty
Keyword(s):  
Continental Shelf ◽  
Internal Wave ◽  
Wave Simulation

scholarly journals Analytical and numerical investigation of nonlinear internal gravity waves

2001 ◽  
Vol 8 (1/2) ◽  
pp. 37-53 ◽  
Author(s):  
S. P. Kshevetskii
Keyword(s):  
Internal Wave ◽  
Analytical Model ◽  
Internal Waves ◽  
Numerical Models ◽  
Wave Mode ◽  
Vertical Acceleration ◽  
Quasistatic Problem ◽  
Wave Simulation ◽  
Non Linear

Abstract. The propagation of long, weakly nonlinear internal waves in a stratified gas is studied. Hydrodynamic equations for an ideal fluid with the perfect gas law describe the atmospheric gas behaviour. If we neglect the term Ͽ dw/dt (product of the density and vertical acceleration), we come to a so-called quasistatic model, while we name the full hydro-dynamic model as a nonquasistatic one. Both quasistatic and nonquasistatic models are used for wave simulation and the models are compared among themselves. It is shown that a smooth classical solution of a nonlinear quasistatic problem does not exist for all t because a gradient catastrophe of non-linear internal waves occurs. To overcome this difficulty, we search for the solution of the quasistatic problem in terms of a generalised function theory as a limit of special regularised equations containing some additional dissipation term when the dissipation factor vanishes. It is shown that such solutions of the quasistatic problem qualitatively differ from solutions of a nonquasistatic nature. It is explained by the fact that in a nonquasistatic model the vertical acceleration term plays the role of a regularizator with respect to a quasistatic model, while the solution qualitatively depends on the regularizator used. The numerical models are compared with some analytical results. Within the framework of the analytical model, any internal wave is described as a system of wave modes; each wave mode interacts with others due to equation non-linearity. In the principal order of a perturbation theory, each wave mode is described by some equation of a KdV type. The analytical model reveals that, in a nonquasistatic model, an internal wave should disintegrate into solitons. The time of wave disintegration into solitons, the scales and amount of solitons generated are important characteristics of the non-linear process; they are found with the help of analytical and numerical investigations. Satisfactory coincidence of simulation outcomes with analytical ones is revealed and some examples of numerical simulations illustrating wave disintegration into solitons are given. The phenomenon of internal wave mixing is considered and is explained from the point of view of the results obtained. The numerical methods for internal wave simulation are examined. In particular, the influence of difference interval finiteness on a numerical solution is investigated. It is revealed that a numerical viscosity and numerical dispersion can play the role of regularizators to a nonlinear quasistatic problem. To avoid this effect, the grid steps should be taken less than some threshold values found theoretically.

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