There is a very good reason why such work is done in FORTRAN: Neither Python, nor Perl are the right tools for PDEs. The reason is that PDEs can be expensive to solve and you want to choose the RIGHT code (e.g. implicit schemes for stiff problems) that runs FAST. Where Perl or any other interpreted language for that matter has a place is as a front-end or backend, for instance a graphical interface to set the parameters and possibly parse the results and create say an Xmgrace graphics file. So the answer is I cannot be certain noone has done a perl implementation of a pde solver, but honestly I'd consider this rather a waste of time.