Why Do We Need Wave Packets in Water Waves?

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Discussion Overview

The discussion revolves around the necessity and significance of wave packets in the context of water waves, particularly in relation to the nonlinear Schrödinger equation (NLSE) and the Korteweg-de Vries (KdV) equation. Participants explore the physical implications and mathematical characteristics of wave packets, as well as their role in soliton theory.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant questions the physical necessity of wave packets in water waves and contrasts this with the KdV equation, suggesting that wave packets may not be needed in that context.
  • Another participant notes that the nonlinear Schrödinger equation can indeed be applied to water waves, indicating a potential connection between the two concepts.
  • A participant proposes that wave packets are special because they can represent particles.
  • It is mentioned that wave packets are among the few analytical solutions to the nonlinear Schrödinger equation.
  • One participant recommends a book on solitons, highlighting the intricate nature of the theory and its relevance to understanding wave packets and related equations.
  • A question is raised about how the KdV equation specifically deals with wave packets.

Areas of Agreement / Disagreement

Participants express differing views on the necessity and role of wave packets in water waves, with some asserting their importance while others question it. The discussion remains unresolved regarding the specific contributions of wave packets compared to the KdV equation.

Contextual Notes

There are references to various equations and their relationships to wave packets, but the discussion does not clarify the assumptions or mathematical steps involved in these connections.

hanson
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Hi all.
Can someone explain me physically why we need to deal with wave packets in water waves?
I know the the nonlinear Schrödinger equations deals with wave packets in water wave.
But why bother dealing with wave packets?
For the KdV equation, the concept of wave packets is not needed, why?
What so special about wave packets?
Please help.
 
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Schroedinger equation deals with water? That's new to me.
 
genneth said:
Schroedinger equation deals with water? That's new to me.

yes, nonlinear Schrödinger equation can be used in water waves context.
Please help.
 
They're special in that they represent particles?
 
hanson said:
What so special about wave packets?
They are one of the very few analytical solutions to the NLSE.
 
Recommend a good book

genneth said:
Schroedinger equation deals with water? That's new to me.

The theory of solitons is a beautiful, intricate, and highly developed subject, so anyone who wants to know more should consult a good book since there is a lot to learn if you want to understand the basics. However, IMO it is not nearly as confusing as hanson makes out!

I like the undergraduate level introduction by P. G. Drazin and R. S. Johnson, Solitons: an Introduction, Cambridge University Press, 1989.

If you follow this up, you will see how the usual Schroedinger equation plays a role in the famous inverse-scattering transform method of solving the KdV, a famous soliton equation, which arises as an approximation of water waves under certain circumstances. This spawned a great deal of work, including analysis of related PDEs, such as the mKdV, the BBM equation, the Camassa-Holm equation, etc. (the latter also arises as approximations of water waves and includes idealized "breaking of waves"; see math.AP/0709.0905).

The nonlinear Schroedinger equation is a nonlinear generalization of the Schroedinger equation which itself has some aspects of a soliton equation. The sine-Gordon equation is another well known nonlinear PDE which has some soliton-like solutions.

You can search the arXiv to find many recent papers discussing current research in this area. Needless to say, you will need a strong background in differential equations to follow this research.
 
How does KdV equation deal with wave packets?
 

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