NUMERICAL-SIMULATION OF THE WICKING EFFECT IN LINER SYSTEMS

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.