Deriving the 2D KdV Equation: A Guide for Overcoming Nonlinear Theory Challenges

In summary, the conversation discusses the derivation of the 2D KdV equation, also known as the KP equation, and the speaker's progress in understanding it. They mention referencing Johnson's 1980 paper on water waves and Kortweg de Vries equations and extending the derivation to include surface tension and an electrical field. The speaker also mentions their contact with Johnson and their discovery of his paper through a footnote in a book. They express their appreciation for the paper's help in overcoming their problem with the derivation and creating visual representations of the solutions.
  • #1
hunt_mat
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Does anyone know of a derivation or has a reference to the derivation of the 2D KdV equation (known as the KP equation I believe). I have done the linear theory for this problem and the results look good but the next stage is the weakly nonlinear theory and I am having trouble with a certain aspect of it.
 
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  • #2
Johnson 1980 Water waves and Kortweg de Vries equations. J Fluid Mech, 97, 701-19
 
  • #3
Okay, I can work with this, Cheers. As an aside I am trying to extend the derivation to include the effect of surface tension and an electrical field. I have done this for one dimension but I have yet to do this for two.

The odd thing is that I was in contact with Johnson about this and he never mentioned this paper of his, weird.
 
  • #4
I haven't seen the paper itself - it came from a footnote at the bottom of page16 "for a review of one and two dimensional KDV equations..." of Drazin and Johnson.
The book itself treats 2D but only in solutions not derivations.
 
  • #5
It's actually quite a good paper, it tells me how I can go about overcoming my problem with the derivation and in that sense it's a very good thing. The linear problem for the 3D case actually wasn't much harder than the 2D case. What took me a while was plotting the solutions but I have not overcome that and I have some very pretty wave pictures.
 

What is the 2D KdV equation and what is its significance?

The two-dimensional Korteweg-de Vries (KdV) equation is a partial differential equation that describes the evolution of a one-dimensional surface wave. It is often used to model physical phenomena such as water waves, plasma waves, and sound waves. Its significance lies in its ability to accurately describe the behavior of these types of waves and its wide applications in various fields of science and engineering.

How was the 2D KdV equation derived?

The 2D KdV equation was derived by Korteweg and de Vries in 1895 as a simplification of the full Euler equations for fluid motion. They assumed the wave amplitude is small and the wave speed is constant, leading to a nonlinear partial differential equation that governs the evolution of the wave's amplitude over space and time.

What are the assumptions made in deriving the 2D KdV equation?

The 2D KdV equation is derived under the assumptions of small amplitude and constant wave speed. It also assumes that the wave is propagating in a homogeneous and inviscid medium, and that the wave's amplitude varies slowly over space and time.

What are the applications of the 2D KdV equation?

The 2D KdV equation has a wide range of applications in various fields of science and engineering. It is commonly used to model water waves in coastal engineering, plasma waves in fusion research, and sound waves in acoustics. It also has applications in nonlinear optics, geophysics, and fluid mechanics.

What are the limitations of the 2D KdV equation?

One of the main limitations of the 2D KdV equation is that it only applies to small amplitude waves and does not take into account nonlinear effects that may occur at larger amplitudes. It also assumes a constant wave speed, which may not always be true in real-world scenarios. Additionally, it does not account for dissipative effects such as viscosity and turbulence. These limitations have led to the development of more complex equations, such as the 3D KdV equation, to better describe wave behavior in different situations.

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