A Numerical Model of Transient Unsaturated Flow Under Centrifugation Based on Mass Balance

作者：Kacur J; Malengier B^*; Kison P

来源：Transport in Porous Media, 2011, 87(3): 793-813.

DOI：10.1007/s11242-011-9719-8

• Richards equation
• Unsaturated-saturated flow
• Method of lines
• Centrifugation

Numerical modeling of unsaturated flow in porous media under centrifugation is studied. A precise and numerically efficient approximation is presented for the mathematical model, based on Richards' nonlinear and degenerate equation expressed in terms of effective saturation using the Van Genuchten-Mualem ansatz. The main difference with other methods is the utilization of a nonlocal condition based on mass balance. The method is suitable for determination of soil parameters, including the saturated conductivity, via the solution of an inverse problem in an iterative way. First, the fully saturated sample is centrifugated with a free outflow boundary during some time interval. Next, the output boundary is sealed and the sample is centrifugated for a prescribed time interval, or up to the creation of an equilibrium. Finally, the centrifugation is continued with a free outflow boundary. This procedure can be repeated to increase the information to drive the inverse problem. The application of the present method requires only non-intrusive, cheap measurements: rotational momentum and/or gravitational center of the sample, and optionally, the amount of expelled water.

• 出版日期2011-4