Simply put, the goal is to integrate the Navier-Stokes equations from time t0 to tn to observe the changes in the state of a fluid. The input to the application defines the problem geometry and the initial conditions of the fluid. An initial velocity field is given by the input data, and the solution is integrated forward in time by numerically solving the equations that describe advection and diffusion of momentum in the fluid. A large number of modes are required to attain high resolution. Slices of the periodic domain are the units of work apportioned to the nodes.
Input data is accessed by all processors.
The mesh consists of quadrilateral elements with a uniform length in the periodic direction of the domain. Initially the number of elements and the x and y coordinates of their vertices are read in, followed by information regarding elements that have curved sides. The mesh is generated, and boundary information is accessed. Matrices for the discrete pressure and velocity equations are built using an additional input file. After the vectors are transformed to Fourier space, the Navier-Stokes calculations are applied to integrate the solution forward in time, and the final results are transformed back to physical space.