A set of C and Fortran computer programs have been developed for computing the permeability of three-dimensional porous media under incompressible Stokes flow conditions. While currently being employed to simulate the permeability of model pervious concretes, the codes have been utilized in the past on a wide variety of model and real (computer tomography) three-dimensional microstructures.
For many years, research in the Materials and Structural Systems Division (formerly the Materials and Construction Research Division) at the National Institute of Standards and Technology (NIST) has focused on understanding the relationship between microstructure and properties, particularly for cement-based materials. For many materials, one key material property is their resistance to fluid flow under a pressure gradient, e.g., their permeability. For the case of laminar (slow, incompressible) flow, the fluid flow can be conveniently described by the linear Stokes nist-equations. This program presents a set of computer codes written in the C and Fortran programming languages to accomplish two purposes: 1) a pre-processor written in C to convert a model or real three-dimensional microstructure (represented by a three-dimensional set of voxels) into lists of coordinates representing the voxels where pressures, x-velocity, y-velocity, or z-velocity components will be present and 2) a set of Fortran programs to numerically solve the linear Stokes nist-equations in three dimensions, using a finite difference scheme in conjunction with the artificial compressibility relaxation algorithm.