Modeling Media with Oriented Structures

Heterogeneity is typically the result of space variability of soil parameters at different scales. Soil anisotropy may be defined as the spatial persistence in some direction only, across coarse-grid elements, of heterogeneous structures with different characteristic lengths in different directions. One can account for the effect of these structures by upscaling soil properties. Analyzing flow in a strongly anisotropic structured soil at different scales evidences how transverse dispersion reduces to a subscale process, leading to mixing within the conductive structures.     

Linear Stability Analysis of Infiltration,Analytical and Numerical Solution

Linear stability analysis is applied to the Richards equation by perturbing the pressure field. An analytical solution of the stability problem of flow through stratified media is presented. It is obtained under two simplifying assumptions: the quasi-steady hypothesis and the quasi-linear hypothesis. Flow is found to be unconditionally stable. A numerical experiment and the comparison with published data supports the conclusion that upscaling capillary phenomena is crucial in order to capture the essence of finger flow by continuum models.