Pencil FFT Implementation in the FLASH Simulation Code

FLASH 3 beta is the latest release of a parallel Adaptive Mesh Refinement (AMR) code for simulating thermonuclear flashes. It can be easily adapted with other modules as required to solve various different physical problems. Poisson’s equation is a second–order partial differential equation which is used to calculate the gravitational force on a system of particles. It can be solved efficiently using Fast Fourier Transform (FFT) algorithms. This project aimed to allow non–uniform grid simulations to use the Pencil FFT (PFFT) library, which requires a uniform grid. This is achieved by remapping the grid into a uniform one which can be used directly by the PFFT code. This project produced an implementation of the algorithm in uniform grid mode and the basic structure required to implement the AMR mode, but did not solve the problems associated with the latter. The project did not produce the library calls required for a working parallel FFT nor did it produce any FFT test cases, although both are discussed.