A 3-DIMENSIONAL AIR-FLOW MODEL FOR SOIL VENTING - SUPERPOSITION OF ANALYTICAL FUNCTIONS

A three-dimensional computer model was developed for the simulation of the soil-air pressure distribution at steady state and specific discharge vectors during soil venting with multiple wells in unsaturated soil. The Kirchhoff transformation of dependent variables and coordinate transforms allowed the adoption of the superposition of analytical functions to satisfy the differential equations and boundary conditions. A venting well was represented with a line source of a finite length in a infinite homogeneous medium. The boundary conditions at the soil surface and the water table were approximated by the superposition of a large number of mirror image wells on the opposite sides of boundaries. The numerical accuracy of the model was checked by the evaluation of one of the boundary conditions and the comparison of a simulation result with an available analytical solution from the literature. Simulations of various layouts of operating systems with multiple wells required minimal computational expenses. The model was very flexible and easy to use, and its numerical results proved to be sufficiently accurate.