Formulating Ripple Equation for 2D Symmetry

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Discussion Overview

The discussion revolves around formulating a two-dimensional ripple equation μ(x,y) that satisfies specific conditions related to symmetry, amplitude, and normalization. Participants explore the mathematical representation of this ripple effect, particularly in the context of modeling water waves.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant outlines the desired properties of the ripple equation, including symmetry about the y-axis, fading amplitude, and non-negative values.
  • Another participant suggests solving the problem in polar coordinates and questions the need for a source function and initial displacement, indicating that limiting the function to positive values may be non-physical.
  • A later reply clarifies the intention to seek a one-dimensional solution, shifting the focus from a two-dimensional representation.
  • Another participant proposes a specific function, y(x) = Ae^{-bx}cos{x}, and emphasizes the importance of deriving a differential equation rather than arbitrarily selecting a function.

Areas of Agreement / Disagreement

Participants express differing views on the dimensionality of the solution and the physical implications of the function's positivity. There is no consensus on the best approach to formulate the ripple equation, and multiple competing views remain regarding the mathematical representation.

Contextual Notes

Participants have not fully resolved the implications of the conditions set for the ripple equation, particularly regarding the physicality of limiting the function to non-negative values and the choice between one-dimensional and two-dimensional formulations.

sodaboy7
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I want to formulate an approx 2D ripple equation μ(x,y). It should satisfy following:

1) it should have highest amplitude on y-axis at x=0. It should be symmetrical about y axis. It should fade away at some x on both positive and negetive x-axis symmetrically. Fading in a way of decreasing amplitude. It should not give negetive value of y.

2) most important. The square of norm of μ should be normalized in infinity.

I am not good at math but this is integral part of my project. It can be visualized as : consider x-axis as still surface of water and you drop a pebble on it. But it should be shifted upwards such that it should not fall in negetive y axis. Also it should be preferably in cartesian co ordinates
 
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Do you mean a "ripple" like function on a plane surface that models a water wave?
Your conditions are:
1.symmetric across the y-axis (simply solve in polar coordinates, with the condition that the function obeys ψ(r,θ)=ψ(r,θ+pi)
2.Falls off at infinity, that's fine we'll just pick a solution that does this

And then simply solve the wave equation in polar coordinates with these conditions.
Ta-da.

However, could you specify how you want it?
There are a few things you have to consider.
1.Source function?
2.Initial displacement?

Also, you cannot limit the function to be positive, that would be non-physical. Real water ripples go both ways.Edit: Now I'm a bit confused, do you want a plane solution or a one dimensional solution? I thought you meant the former, seeing as you referred to the function as a "ripple equation" and specified two arguments for it (mu(x,y)), but then I read your conditions again and you also imply you want a one dimensional one. (i.e. y(x))
 
Last edited:
HomogenousCow said:
Do you mean a "ripple" like function on a plane surface that models a water wave?
Your conditions are:
1.symmetric across the y-axis (simply solve in polar coordinates, with the condition that the function obeys ψ(r,θ)=ψ(r,θ+pi)
2.Falls off at infinity, that's fine we'll just pick a solution that does this

And then simply solve the wave equation in polar coordinates with these conditions.
Ta-da.

However, could you specify how you want it?
There are a few things you have to consider.
1.Source function?
2.Initial displacement?

Also, you cannot limit the function to be positive, that would be non-physical. Real water ripples go both ways.


Edit: Now I'm a bit confused, do you want a plane solution or a one dimensional solution? I thought you meant the former, seeing as you referred to the function as a "ripple equation" and specified two arguments for it (mu(x,y)), but then I read your conditions again and you also imply you want a one dimensional one. (i.e. y(x))

I did a silly mistake there, I want 1D solution of it. :-P
 
I want it in form y(x)
 
y(x) = Ae^{-bx}\cos{x} fits the bill. What exactly are you trying to model? You're better off deriving a differential equation and trying to solve it than just picking out a function from random that meets certain requirements.
 

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