scholarly journals Time-Reversal Analogy by Nonlinear Acoustic–Gravity Wave Triad Resonance

Fluids ◽  
2019 ◽  
Vol 4 (2) ◽  
pp. 91 ◽  
Author(s):  
Usama Kadri
Keyword(s):  
Wave Packet ◽  
Gravity Wave ◽  
Time Reversal ◽  
Sudden Change ◽  
Wave Theory ◽  
Acoustic Mode ◽  
Acoustic Gravity Wave ◽  
Surface Gravity Wave ◽  
Energy Pumping ◽  
Nonlinear Acoustic

Time reversal of free-surface water (gravity) waves due to a sudden change in the effective gravity has been extensively studied in recent years. Here, we show that an analogy to time-reversal can be obtained using nonlinear acoustic-gravity wave theory. More specifically, we present a mathematical model for the evolution of a time-reversed gravity wave packet from a nonlinear resonant triad perspective. We show that the sudden appearance of an acoustic mode in analogy to a sudden vertical oscillation of the liquid film, can resonate effectively with the original gravity wave packet causing energy pumping into an oppositely propagating (time-reversed) surface gravity wave of an almost identical shape.

scholarly journals Lagrangian transport for two-dimensional deep-water surface gravity wave groups

2016 ◽  
Vol 472 (2192) ◽  
pp. 20160159 ◽  
Author(s):  
T. S. van den Bremer ◽  
P. H. Taylor
Keyword(s):  
Gravity Wave ◽  
Frequency Dispersion ◽  
Wave Theory ◽  
Stokes Drift ◽  
Surface Gravity ◽  
Return Flow ◽  
Surface Gravity Wave ◽  
Wave Groups ◽  
Lagrangian Transport ◽  
Separation Of Scales

The Lagrangian trajectories of neutrally buoyant particles underneath surface gravity wave groups are dictated by two physical phenomena: the Stokes drift results in a net displacement of particles in the direction of propagation of the group, whereas the Eulerian return flow, as described by the multi-chromatic wave theory of Longuet-Higgins & Stewart (1962 J. Fluid Mech. 13 , 481–504. ( doi:10.1017/S0022112062000877 )), transports such particles in the opposite direction. By pursuing a separation of scales expansion, we develop simple closed-form expressions for the net Lagrangian displacement of particles. By comparing the results from the separation of scales expansion at different orders in bandwidth, we study the effect of frequency dispersion on the local Lagrangian transport, which we show can be ignored for realistic sea states.

scholarly journals On the origin of medium-period ionospheric waves and their possible modelling: a short review

1997 ◽  
Vol 40 (5) ◽  
Author(s):  
P. Dominici ◽  
L. R. Cander ◽  
B. Zolesi
Keyword(s):  
Data Analysis ◽  
Gravity Wave ◽  
Gravity Waves ◽  
Sudden Change ◽  
Short Review ◽  
Acoustic Gravity Wave ◽  
Acoustic Gravity Waves ◽  
Physical Conditions ◽  
Wave Induced ◽  
The Waves

This article introduces the concept of ionospheric waves with periods from about 15 min to about 4 h as one of the acoustic-gravity wave-induced phenomena. The existence of these medium-period ionospheric waves in the various ionospheric layers is supported by the results of a data analysis which has shown remarkable characteristics in occurrence and direction of the waves with a period not longer than about 2 h. The explanation offered is based on the assumption that a unique phenomenon capable to launch acoustic-gravity waves related to such ionospheric waves is the sudden change in physical conditions of the atmosphere due to the passage of the solar terminator.

Influence of the upper atmosphere inhomogeneity on acoustic gravity wave propagation

2012 ◽  
Vol 18 (4(77)) ◽  
pp. 30-36 ◽  
Author(s):  
Y.I. Kryuchkov ◽  
◽  
O.K. Cheremnykh ◽  
A.K. Fedorenko ◽  
◽  
...  
Keyword(s):  
Wave Propagation ◽  
Gravity Wave ◽  
Upper Atmosphere ◽  
Acoustic Gravity Wave
Sign in / Sign up

Export Citation Format

Share Document