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Mathematical Problems in Engineering
Volume 2011, Article ID 163020, 23 pages
http://dx.doi.org/10.1155/2011/163020
Research Article

Using Global Characteristics of a Centrifuge Outflow Experiment to Determine Unsaturated Soil Parameters

1Faculty of Mathematics, Physics and Informatics, Comenius University Bratislava, Mlynská dolina, 84248 Bratislava, Slovakia
2Department of Mathematical Analysis, Research Group NaM2, Ghent University, Galglaan 2, B 9000 Gent, Belgium

Received 29 March 2011; Revised 8 September 2011; Accepted 15 September 2011

Academic Editor: J. Rodellar

Copyright © 2011 Jozef Kačur et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Several centrifugation scenarios enabling the determination of soil parameters for saturated-unsaturated flow in porous media are presented, investigated, and discussed. Only global characteristics of the infiltration process in a sample are used, so that only simple, noninvasive measurements are performed. The characteristics can be transient measurements of the rotational momentum, or of the gravitational center, or of the water amount injected and expelled from the sample. No information about the saturation or the head distribution in the sample is required. This setup is different from the common multioutflow experiments. We give numerical proof that this method allows for fast determination of soil parameters in comparison to traditional measurements based on equilibrium conditions. The mathematical model of infiltration is represented by Richards' strongly nonlinear and degenerate equation expressed in terms of soil parameters in the van Genuchten-Mualem ansatz. The parameter identification process is realized in an iterative way applying the Levenberg-Marquardt method. Numerical experiments support the efficiency of the analyzed method and allow one to identify the optimal centrifugation scenario for imbibition and drainage to be applied when using global characteristics.