Numerical Simulation of the Wicking Effect in Liner Systems

Abstract

Numerical simulations were carried out to investigate the capillary barrier effect and the wicking ability of multilayer earth liner systems. Two specific cases were studied: a two‐layer liner composed of a fine‐ over a coarse‐textured material, and a three‐layer liner composed of a medium‐textured material in between a fine‐ and a coarse‐textured material. Results of the simulations show that a quadratic relationship exists between the thickness of the fine‐textured material and the arrival time of the wetting front to the interface. At the time the wetting front reaches the interface, the width of the lateral spreading within the fine material is smaller than the thickness of this material. The lateral spreading and thickness are linearly related. The wicking ability of the different materials is more significant under relatively smaller infiltration rates and is controlled by the magnitude of the hydraulic diffusivity. For the two‐layer liner the criteria of minimizing the vertical movement and maximizing the wicking effect within the fine‐textured material conflict. A three‐layer liner satisfies both of these criteria. The results for the three‐layer system show that the medium‐textured material has more superior wicking properties than the fine material does.

Monotonicity Considerations for Saturated--Unsaturated Subsurface Flow

“…in either equation (23) or (27) and noting that node i is a homogeneous node (equations (29) and (30)), we obtain …”

“…Also, the capillary pressure and relative permeability curves in different materials can be very different. These materials can be the naturally occurring soil or rock formations, or they can be part of an engineered design of a waste storage facility [10,22,11,21,29].…”

Numerical simulation of the Rhade effect in layered aquifer systems due to groundwater pumping shutoff

“…The material properties of sand and clay, which compose the layered aquifer system, are obtained from Jumikis [14] and Yeh et al [38] and listed on the second and third columns, respectively, in Table 1. These properties are typical of unconsolidated sandy and clayey materials.…”

Capillary barrier performance in heterogeneous porous media

“…The entire domain is tilted 5 ø clockwise by rotating the gravity vector in the simulations. Because the focus of this study is on the relative effects of different heterogeneous configurations, only steady state conditions are considered (the reader is referred to Yeh et al [1994] for transient responses of capillary barrier systems consisting of homogeneous layers).…”