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I posted the question below in Stackoverflow but then realized that it perhaps would find a better audience here.

I am solving a fourth order non-linear partial differential equation in time and space (t, x) on a square domain with periodic or free boundary conditions with MATHEMATICA.

Without using conformal mapping, what boundary conditions at the edge or corner could I use to make the square domain "seem" like a circular domain for my non-linear partial differential equation which is cartesian?

The options I would not like to use are:

  • Conformal mapping
  • changing my equation to polar/cylindrical coordinates?

This is something I am pursuing purely out of interest just in case someone screams bloody murder if misconstrued as a homework problem! :P


If I have a result from solving a PDE in cartesian coordinates, how do I transfer these results or view them in polar coordinates?

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Your question is quite imprecise; I don't understand what you mean for a square to "look" or "seem" like a circle. It might help if you explained what you find unsatisfactory about conformal mapping and polar coordinates. – Rahul Feb 20 '12 at 4:32
@RahulNarain If I have results of a PDE in cartesian coordinates, how do I transfer them to polar coordinates? – drN Feb 20 '12 at 16:53

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