FDFLOW: a FORTRAN-77 solver for 2-D incompressible fluid flow

Abstract In this work, a FORTRAN-77 program for solving two-dimensional (2-D) incompressible flows is presented. The algorithm is based on finite difference approximations of the momentum and continuity equations, and consists of two stages. In the first stage, a temporary field is obtained using conservative approximations of the momentum equations, either implicit or explicit, with the old pressure gradient. In the second stage, the advanced-time velocity and pressure are obtained using an iterative method, in such a way that the incompressibility constraint is satisfied. The program was written in a modular form, and can be used to obtain accurate solutions to some difficult fluid-flow problems with small PCs. This capability was tested by its application to lid-driven cavity flow and flow past a backward-facing step, with Reynolds number up to 10,000. The model described herein might be useful for both educational and professional purposes. Because of its simple design, the program can be taken as a starting point to test other numerical schemes, or to treat more advanced problems than those considered in this work, such as thermally coupled flow, free-surface flow, and 3-D flow.