years as a graduate assistant in the physics department. He did additional graduate work at the University of During 1902 to 1906 as a soil physicist at the USDA Bureau of Strasbourg and the University of Leipzig, where he studSoils (BOS), Edgar Buckingham originated the concepts of matric ied under chemist Wilhelm Ostwald, who won the Nobel potential, soil–water retention curves, specific wate...

We present a numerical analysis of an implicit time discretization method applied to Richards’ equation. Written in its saturation-based form, this nonlinear parabolic equation models water flow into unsaturated porous media. Depending on the soil parameters, the diffusion coefficient may vanish or explode, leading to degeneracy in the original parabolic equation. The numerical approach is base...

We study flow problems in unsaturated porous media. Our main interest is the gravity driven penetration of a dry material, a situation in which fingering effects can be observed experimentally and numerically. The flow is described by either a Richards or a two-phase model. The important modelling aspect regards the capillary pressure relation which can include static hysteresis and dynamic cor...

Development und experimental testing of a new kind of dielectric barrier discharge flow reactors applicable for plasma-assisted chemical vapor deposition as well as surface treatment processes at atmospheric pressure are described. Using a combination of two upstream modules, a gradient mixer and a homogenizer, the reactor is fed by a laminar gas flow with an established concentration gradient ...

The weak formulation of moving boundary problems with possibly vanishing specific heat, that is governed by parabolic and/or elliptic differential equations, is developed. The uniqueness of the resulting weak solution is then proved. This approach is used to obtain numerical solutions to some physical examples, which arise in electrochemical machining processes, and in saturated / unsaturated f...

Abstract. A PDE system consisting of the momentum balance, mass balance, and energy balance equations for displacement, capillary pressure, and temperature as a model for unsaturated fluid flow in a porous viscoelastoplastic solid is shown to admit a solution under appropriate assumptions on the constitutive behavior. The problem involves two hysteresis operators accounting for plastic and capi...

et al., 1995, 1996; Szabo et al., 1996), flow and groundwater quality (Johnston et al., 1998; Böhlke and Denver, Transport of chlorofluorocarbon (CFC) gases through the unsatu1995), and groundwater–surface water interactions (Katz rated zone to the water table is affected by gas diffusion, air–water et al., 1995). A critical component in such analyses is the exchange (solubility), sorption to t...

Abstract. Degenerate parabolic variational inequalities with convection are solved by means of a combined relaxation method and method of characteristics. The mathematical problem is motivated by Richard’s equation, modelling the unsaturated – saturated flow in porous media. By means of the relaxation method we control the degeneracy. The dominance of the convection is controlled by the method ...

In this study, the remediation performance of electrokinetic (EK) technology integrated with different surfactants for removing phenanthrene from unsaturated soils was investigated. A synthetic surfactant (Triton X-100) and a biosurfactant (rhamnolipid) were used to enhance phenanthrene solubility and removal efficiency during EK process. Results indicate that the electro-osmotic flow (EOF) rat...

During a rainfall water infiltration into an unsaturated soil, zones of saturation may be developed anywhere within the flow domain. Consequently, a natural question arises: under which conditions depending on the rate at which rain water is supplied, the initial moisture distribution in the soil, the presence of underground sources and the boundary permeability, the flow domain may be separate...