# International Association for Hydro-Environment Engineering and Research

IAHR, founded in 1935, is a worldwide independent member-based organisation of engineers and water specialists working in fields related to the hydro-environmental sciences and their practical application. Activities range from river and maritime hydraulics to water resources development and eco-hydraulics, through to ice engineering, hydroinformatics, and hydraulic machinery.
 You are here : eLibrary : IAHR World Congress Proceedings : 34th Congress - Brisbane (2011) : THEME 7: Hydroinformatics : Comparison of numerical techniques for the solution of richards’ equation
 Comparison of numerical techniques for the solution of richards’ equation Author : D.E.Caviedes-Voulličme, P.García-Navarro and J.Murillo Flow in variably saturated soils is described by Richards’ equation. This PDE is commonly found in three physically equivalent forms which lead to different discretization techniques. Such techniques show different properties and range for variably saturated soil simulations. Furthermore, the properties of the soil constitutive model interact with the numerical techniques and affect their response in several ways. Our goal is to evaluate the numerical solution of the three PDE’s using well-known numerical methods from the point of view of mass conservation, convergence and computational efficiency to set a framework for a 3D variably saturated soil model with surface interactions. The interrelated effects of the PDE's, numerical schemes and saturated/unsaturated conditions are explored. Additionally, the effects of non-linearity of the soil constitutive model functions, as well as those of hydraulic conductivity averaging on intercell boundaries are also studied. A validation case is presented and the response to different configurations and parameters is examined. From them, it is concluded that the explicit and the implicit schemes based on the mixed form of Richards’ equation are better suited for unsaturated problems. For variably saturated problems, the implicit scheme based on the mixed form is the best choice, since the explicit model cannot solve saturation conditions. Conditional stability of the explicit model affects negatively its performance in certain cases, which also leads to the conclusion that the implicit scheme is more efficient and reliable. File Size : 1,831,087 bytes File Type : Adobe Acrobat Document Chapter : IAHR World Congress Proceedings Category : 34th Congress - Brisbane (2011) Article : THEME 7: Hydroinformatics Date Published : 01/07/2011 Download Now