Finding Wavevector in 2D Domain

[Crot]

Dear forumers,

There is a wave computed in a 2D domain.
Could you please give me a hint how to find the wavevector of the wave?
I think I have to Fourier transform the wave in space but I cannot figure out how to
obtain that k_x and k_y from the transformation.


Crot

 

[olivermsun]

There other ways to do this, but FFT is a straightforward (if brute force) approach.

You will want to look up the reference for your FFT routine (if you are using a prepackaged one). Typically, the FFT will give you amplitudes for +/- k_x, k_y with the index being wavenumber expressed as integer multiples of cycles per domain length (since the longest periodic wave in the domain completes 1 cycle). However, for the N-point FFT, you will likely get an order like -N/2, -N/2+1, ..., 0, N/2-1 cycles per domain for even N (or -N/2,...,0,...,N/2 for an odd N).

Anyway you are just looking for the peak wavenumbers in both k_x and k_y, right?

 

[Crot]

Thanks a lot for the answer. Now, it is clear!