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Unsaturated Flow in Fractures with Anisotropic Variable Apertures

Author(s): C. Masciopinto; M. Benedini

Linked Author(s): Marcello Benedini

Keywords: Fractured media; Unsaturated flow; Numerical model

Abstract: Vertical movement of water in a fracture plane under unsaturated condition has been investigated by means of a computational code. The relevant conceptual model is based on a 2D approximation of the generalized Darcy law. Portion of the fracture is occupied by wetting and non-wetting phases, respectively, according to the capillary pressure and global accessibility criteria. The finite difference method was used in the computational code to solve the nonlinear set of equations. An internal iteration method was used at every time step to evaluate the nodal value of the pressure head, in agreement with the mass-balance equation and the characteristic functional relationships of the coefficients. The variable apertures were calculated by means a spatial correlation matrix which can be considered also anisotropic. The code results were tested with results known in the literatures for isotropic correlation of fracture apertures. A fingering effect in the pressure head distribution within the fracture plane was noted. The application of the code to a fracture with anisotropic aperture variability showed a reduction of the fingering due to larger values of apertures selected, in the x direction.


Year: 1999

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