A boundary integral equation method for steady twodimensional flow in partially saturated media
Abstract
The governing equation for steady flow in a partially saturated, porous medium can be written in a linear form if one adopts a hydraulic conductivity function that is exponential in the capillarypressure head. The resulting linear field equation is well suited to numerical solution by the boundary integral equation method (BIEM). The exponential conductivity function is compared to a more complex form often assumed for tuffs, and is found to be a reasonable approximation over limited ranges of pressure head. A computer code based on the BIEM is described and tested. The BIEM is found to exhibit quadratic convergence with element size reduction on smooth solutions and on singular problems, if mesh grading is used. Agreement between results from the BIEM code an a finiteelement code that solves the fully nonlinear problem is excellent, and is achieved at a substantial advantage in computer processing time.
 Publication:

NASA STI/Recon Technical Report N
 Pub Date:
 July 1991
 Bibcode:
 1991STIN...9131573M
 Keywords:

 Boundary Integral Method;
 Computer Programs;
 Computerized Simulation;
 Fluid Flow;
 Integral Equations;
 Porous Materials;
 Steady Flow;
 Two Dimensional Flow;
 Convergence;
 Exponential Functions;
 Finite Element Method;
 Flow Equations;
 Linear Equations;
 Nonlinear Systems;
 Pressure Heads;
 Fluid Mechanics and Heat Transfer