3dimensional wave propogation.

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Discussion Overview

The discussion revolves around the mathematical representation of three-dimensional sine waves, particularly focusing on their behavior and characteristics in various contexts. Participants explore functions that describe these waves and their applications in wave propagation.

Discussion Character

  • Exploratory
  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant inquires about a function representing a 3D sine wave with the z-axis on the circumference of a circle.
  • Another participant suggests that while the equation for symmetric longitudinal waves in 3D is straightforward, symmetric transverse waves may not have a solution.
  • A participant shares a potential function, z = sin(√(x² + y²)), found through visual examples, expressing interest in wave behavior without a specific study context.
  • There is a mention of misunderstanding regarding the symmetry of the wave, with a participant expressing interest in the implications of symmetry in three dimensions.
  • One participant proposes solving the wave equation in three dimensions, suggesting that for isotropic propagation, all angular derivatives can be set to zero.
  • Another participant provides an example of a 3D plane wave function, f(x,y,z,t) = sin(k_x x + k_y y + k_z z - ω t), reflecting a general interest in waves.
  • A discussion on axisymmetric 2D waves in surface wave propagation is introduced, with reference to the form sin(kr - ωt) for r = √(x² + y²), and a mention of radially symmetric 3D waves for acoustic waves from a point source.

Areas of Agreement / Disagreement

Participants express varying interpretations of the original question, indicating a lack of consensus on the specific requirements for the wave function. Multiple competing views on the nature of the waves and their mathematical representations remain present.

Contextual Notes

Some participants note uncertainty regarding the original poster's intent and the specific characteristics of the waves being discussed, highlighting the need for clearer definitions and assumptions.

Bradyns
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I thought the maths area would be the best place to ask..

What kind of function would represent a 3 dimensional sine wave?
A sine wave, where the z-axis lays on the circumference of a circle.
 
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Bradyns said:
I thought the maths area would be the best place to ask..

What kind of function would represent a 3 dimensional sine wave?
A sine wave, where the z-axis lays on the circumference of a circle.

What is the context of the question? The equation for a symmetric longitudinal wave in 3-D is straightforward, I think. But I'm not sure there is a solution for symmetric transverse waves in 3-D...
 
Essentially, the function for this:
sinani2.gif


There isn't really a context, I'm not currently studying anything relating to this, it just interests me to see the behaviour of waves.

I seem to have found it, by looking for an example image.
z = sinx(√(x2+y2))
 
Bradyns said:
Essentially, the function for this:
sinani2.gif


There isn't really a context, I'm not currently studying anything relating to this, it just interests me to see the behaviour of waves.

I seem to have found it, by looking for an example image.
z = sin(\sqrt{x^{2}+y^{2}})

Oh, I misunderstood your question then. I thought you wanted it to be symmetric in 3 dimensions, not just 2.
 
berkeman said:
Oh, I misunderstood your question then. I thought you wanted it to be symmetric in 3 dimensions, not just 2.

Actually, that would be interesting..

Thank you for the assistance though. ^_^
 
Just solve the wave equation in three dimensions, if you are only interested in isotropic propagation then set all the angular derivatives to zero.
 
HomogenousCow said:
Just solve the wave equation in three dimensions, if you are only interested in isotropic propagation then set all the angular derivatives to zero.

I think like others I am not certain what the OP really meant, but I interpreted the question this way too - perhaps because I have a general interest in waves. Anyway, an example of a 3D plane wave would be:
<br /> f(x,y,z,t) = \sin\left(k_x x + k_y y + k_z z - \omega t \right)<br />
 
The axisymmetric 2d wave is of interest in surface wave propagation from a point source. There you examine sin (kr-ωt) where r= sqrt(x^2 + y^2).

The radially symmetric 3d wave arises for acoustic (pressure) waves emanating from a point source. The relevant plane wave has the form sin (kr - ωt) for r = sort(x^2 + y^2 + z^2) as jasonRF states above.
 

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