OVERFLOW, from NASA Ames, is a thin-layer Navier-Stokes code that utilizes overlapped grids. A PVM-based parallel version distributes the computation for each grid zone onto its own processor and uses interpolation to resolve flow field values in the overlapping regions. The solution method is typically the ARC3D approximate factorization method. Multigrid and low Reynolds number preconditioning have recently been added to OVERFLOW.
OVERFLOW is a focal point of a NASA project that uses derivatives for shape optimization and inverse problems. The projected problems are expected to be large, and, more significantly, need a large number of derivatives.