3dimensional wave propogation.

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The discussion centers on the representation of a three-dimensional sine wave, with participants exploring various mathematical functions. A key function mentioned is z = sin(√(x² + y²)), which describes wave behavior in three dimensions. The conversation also touches on the wave equation for isotropic propagation, suggesting that angular derivatives can be set to zero for simplification. Additionally, examples of both plane waves and radially symmetric waves are provided, highlighting their relevance in acoustic wave propagation. Overall, the thread emphasizes the mathematical complexity and interest in understanding 3D wave dynamics.
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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 propogation 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 propogation 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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