FULL AND BOUNDARY-LAYER SOLUTIONS OF THE STEADY AIR SPARGING PROBLEM

The one previous analytical solution to the steady sparging problem in a homogeneous soil was in the boundary-layer approximation that negle cts the vertical capillary pressure gradient. The present study gives an analytical solution to the full air-flow equation, with the corresp onding boundary-layer solution for comparison. The full solution predi cts sparging below the air-injection point, whereas the boundary-layer solution does not. Solutions are expressed both in terms of the dimen sionless Kirchhoff potential theta (increasing monotonically with capi llary pressure and air saturation also) and the dimensionless Stokes s tream function F (mapping the pattern of air flow). Both theta and F s how the full solution predicting more effective sparging near the inje ction point than does the boundary-layer solution. The overall boundar y-layer relative error, however, decreases as dimensionless air-inject ion depth below the undisturbed water-table increases. (C) 1998 Elsevi er Science B.V. All rights reserved.