I am simulating the evolution of a liquid film through the solution of a 4th order nonlinear partial differential equations.
Of late, I began experimenting with DFT of the result that I have.
My initial film profile looks like this:
And it's DFT looks like this:
A close-up of the DFT reveals that I have a DC value and there are 2 wiggles in X and 2 wiggles in the Y direction and that these are the major frequencies:
However, plotting this as a line plot shows:
What is the spike at the corner? I guess it is the matrix plot from before but why the spike?
Now, at a later stage, my film rupture and looks such as this:
And the DFT and the line plots look like:
So does this DFT show that "other" frequencies are now involved? And What is with the second spike in the right corner of my line plot?