Algorithms for Solving Darcian Flow in Structured Porous Media

This paper presents several algorithms that were implemented in DRUtES [1], a new open source project. DRUtES is a finite element solver for coupled nonlinear parabolic problems, namely the Richards equation with the dual porosity approach (modeling the flow of liquids in a porous medium). Mass balance consistency is crucial in any hydrological balance and contaminant transportation evaluations. An incorrect approximation of the mass term greatly depreciates the results that are obtained. An algorithm for automatic time step selection is presented, as the proper time step length is crucial for achieving accuracy of the Euler time integration method. Various problems arise with poor conditioning of the Richards equation: the computational domain is clustered into subregions separated by a wetting front, and the nonlinear constitutive functions cover a high range of values, while a very simple diagonal preconditioning method greatly improves the matrix properties. The results are presented here, together with an analysis

NUMERICAL SIMULATION OF A SINGLE RING INFILTRATION EXPERIMENT WITH hp-ADAPTIVE SPACE-TIME DISCONTINUOUS GALERKIN METHOD

We present a novel hp-adaptive space-time discontinuous Galerkin (hp-STDG) method for the numerical solution of the nonstationary Richards equation equipped with Dirichlet, Neumann and seepage face boundary conditions. The hp-STDG method presented in this paper is a generalization of a hp-STDG method which was developed for time dependent non-linear convective-diffusive problems. We describe the method and the single ring experiment, and then we present a numerical experiment which clearly demonstrates the superiority of the hp-STDG method over a discontinuous Galerkin method based on a static fine mesh

Uncertainty Updating in the Description of Coupled Heat and Moisture Transport in Heterogeneous Materials

To assess the durability of structures, heat and moisture transport need to be analyzed. To provide a reliable estimation of heat and moisture distribution in a certain structure, one needs to include all available information about the loading conditions and material parameters. Moreover, the information should be accompanied by a corresponding evaluation of its credibility. Here, the Bayesian inference is applied to combine different sources of information, so as to provide a more accurate estimation of heat and moisture fields [1]. The procedure is demonstrated on the probabilistic description of heterogeneous material where the uncertainties consist of a particular value of individual material characteristic and spatial fluctuations. As for the heat and moisture transfer, it is modelled in coupled setting [2]

Microwave processing of cement and concrete materials - towards an industrial reality?

Each year a substantial body of literature is published on the use of microwaves to process cement and concrete materials. Yet to date, very few if any have lead the realisation of a commercial scale industrial system and is the context under which this review has been undertaken. The state-of the–art is evaluated for opportunities, and the key barriers to the development of new microwave-based processing techniques to enhance production, processing and recycling of cement and concrete materials. Applications reviewed include pyro-processing of cement clinker; accelerated curing, non-destructive testing and evaluation (NDT&E), and end-of-life processing including radionuclide decontamination

Funkce urbánních půd, ochrana zemědělských půd a možnosti využití brownfields

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Numerical solution of the flow and transport equations with the dual permeability conceptual approach

The problem of predicting fluid movement in a variably saturated porous medium is important in many fields ranging from agriculture via hydrology to technical applications of dangerous waste disposal in a deep rock formations. Numerical approximation of the coupled processes of the Darcian flow and soluble contaminant transport is intensively studied since 70th of the last century, nevertheless search for an accurate and reliable method is is still a subject of a recent scientific investigation.As the problem of a search for a generally reliable finite element approximation of the Richards' equation is extendible beyond the limits of this thesis, this proposed work focuses mainly on problems associated with the Civil Engineering area, particularly it is a numerical approximation of transport processes related to a problem of the nuclear waste facility Richard, Litoměřiice, the Czech Republic. Computer program DRUtES has been released as a part of this research, it is a two dimensional finite element solver of the coupled model - a variably saturated flow and a soluble transport with a dual permeability conceptual approach.The problem of predicting fluid movement in a variably saturated porous medium is important in many fields ranging from agriculture via hydrology to technical applications of dangerous waste disposal in a deep rock formations. Numerical approximation of the coupled processes of the Darcian flow and soluble contaminant transport is intensively studied since 70th of the last century, nevertheless search for an accurate and reliable method is is still a subject of a recent scientific investigation.As the problem of a search for a generally reliable finite element approximation of the Richards' equation is extendible beyond the limits of this thesis, this proposed work focuses mainly on problems associated with the Civil Engineering area, particularly it is a numerical approximation of transport processes related to a problem of the nuclear waste facility Richard, Litoměřiice, the Czech Republic. Computer program DRUtES has been released as a part of this research, it is a two dimensional finite element solver of the coupled model - a variably saturated flow and a soluble transport with a dual permeability conceptual approach.katedra hydromeliorací a krajinného inženýrstv

Využití biologických prostředků na ochranu brambor vůči mandelince bramborové

The aim of the work was to verify possibilities of biological control against Colorado potato beetle by using cultivated indigenous entomopathogenic fungi and entomopathogenic nematodes from potato fields in Czech Republic before chemical treatment or ecological agriculture and verify their efficacy against Colorado potato beetle. All results are included in attached charts or tables

An adaptive time discretization of the classical and the dual porosity model of Richards’ equation

AbstractThis paper presents a numerical solution to the equations describing Darcian flow in a variably saturated porous medium—a classical Richards’ equation model Richards (1931) [1] and an extension of it that approximates the flow in media with preferential paths—a dual porosity model Gerke and van Genuchten (1993) [8]. A numerical solver to this problem, the DRUtES computer program, was developed and released during our investigation. A new technique which maintains an adaptive time step, defined here as the Retention Curve Zone Approach, was constructed and tested. The aim was to limit the error of a linear approximation to the time derivative part. Finally, parameter identification was performed in order to compare the behavior of the dual porosity model with data obtained from a non-homogenized fracture and matrix flow simulation experiment

The layering of a mountain podzol can strongly affect the distribution of infiltrated water in the soil profile

The layering of the soil profile can influence the accumulation of infiltrated water and the way in which subsurface runoff is formed. This paper examines a mountain podzol characterized by clearly developed soil horizons. After these horizons had been identified, distinct soil layers were defined (the eluvial horizon, the spodic horizon (undifferentiated), and weathered bedrock). Saturated hydraulic conductivity (Ks), particle size distribution and bulk density were measured in these layers. A visualization of the distribution of infiltrated water in the podzolic profile was performed using a dye tracer experiment. The accumulation of dyed water and a distinct lateral flow were detected in the eluvial layer. Only limited entry of water into the spodic layer was observed. These effects were caused by changes in soil hydraulic properties (SHP) among the investigated layers. For the spodic horizons, the measured Ks value (crucial SHP) was significantly lower than the Ks values for the other tested horizons. The probable reason for the lower Ks was an accumulation of fine particles and various substances in the spodic horizons, and corresponding changes in the porous system. The observed effects of layering indicate that water can be accumulated and subsurface runoff can be formed over the spodic layer during intensive rain or snow melting