Bild von Institut mit Institutslogo
homeicon uni sucheicon suche siteicon sitemap kontakticon kontakt
unilogo Universität Stuttgart
Institut für Wasserbau - IWS

Selected Topics and International Network Lectures (WS 2006/07)


noch laufendeSS-2008WS-2007/08SS-2007WS-2006/07SS-2006WS-2005/06SS-2005WS-2004/05(vor WS-2004/05)

16:00 Uhr
Diganta Bhusan Das, PhD
Departmental Lecturer in Chemical Engineering
Department of Engineering Science
University of Oxford

Mechanics of Fluid Flow in Coupled Free and Porous Domain

Fluid flow problems which involve coupled free (fluid) and porous domains are frequently found in hydro-environmental conditions, e.g., interactions between underground lake-saturated subsurface; flow in large fissures, vuggy aquifers and, others. One major lacunas found in the mathematical models of combined free and porous flow domains in the subsurface is that the models impose continuity of the flow/transport parameters to describe the flow behaviour at the interfaces between the two zones. Prescription of such interfacial conditions cannot always be physically justified, as demonstrated by experiments, and, may result in ill posed mathematical formulation of the problem. This talk will present the speakers attempt on developing numerical models of coupled free and porous flow for the subsurface. It is well known that, in some cases, fluid circulates in coupled domains (flow cells) because of variable fluid pressure distribution. The development of the flow cells will be discussed along with the implications of media heterogeneities on these flow patterns.

16:00 Uhr
Prof. Dr. Thilo Streck
Fg. Biogeophysik
Institut für Bodenkunde und Standortslehre
Universität Hohenheim

Solute transport in heterogeneous soils


If applied to real field situations simulation models have to cope with the intrinsic heterogeneity of field soils and the variability of boundary conditions. Complex approaches often fail here because the spatial distribution of parameter functions can in general not be measured (or otherwise assessed) with sufficient accuracy. The boundary conditions are often partly unknown. By way of several case studies, I will illustrate typical sources of variability encountered in applications and present simplified approaches that were successful in modeling the fate of environmental chemicals in field soils at different scales.

16:00 Uhr
Dr. C. Kuells
Institut für Hydrologie
Universität Freiburg

The role of snow-melt events on runoff generation and groundwater recharge -- how isotopes reveal scale effects and climate impacts


Time series analysis of environmental tracers combined with hydrological observations and models provides insight into processes of runoff generation and groundwater recharge. The natural integration of temporal and spatial variability of stable isotope data (oxygen-18, deuterium) at different scales of hydrological systems can be used as a basis for the study of catchment response to climate variability and change. This approach is demonstrated using monitoring data of runoff, groundwater levels, stable isotope and chemical composition at the meso-scale Dreisam catchment (Black Forrest, Germany). The observations reveal that the serious hydrologic drought in summer 2003 was preceded by deviations from the hydrologic and isotopic regime. The departure from a regular seasonal variation started already during winter and spring 2002/2003 - half a year before the hydrological drought became obvious. Isotope data suggest that the lack of intense groundwater recharge from snow-melt due to a warmer than average winter season aggravated the drought of 2003. Further investigations showed a scale-dependent and event-dependent percentage of snow-melt contributions to runoff and groundwater recharge. As a result the role of snow-melt for groundwater regimes needs to be reviewed. Climate changes resulting in different snow-melt conditions might have non-linear impacts on the water balance of catchments and aquifers. Environmental tracers provide methods for the integrated study of these processes at different scales.

16:00 Uhr
Dr. Mattias Schmidt
Proctor & Gamble

Product Development for Consumer Goods: "Boring or Real Science?"

Procter & Gamble is one of the largest consumer products companies in the world. A common misperception is that "development of consumer products is not challenging for scientists or engineers" and that "all you need is good marketing". However, a key part of P&G´s success model is to innovate with superior technology and R&D is a key driver of innovation.
This presentation gives some insights into the world of research and development and the science behind everyday products at P&G. A range of examples will be provided including how we are applying Modeling & Simulation in our everyday work.
Dr. Mattias Schmidt is a physicist and works as a Research Fellow in R&D BabyCare. He has worked for 15 years in the area of fluid flow and absorbency with particular application to baby diapers.

16:00 Uhr
Dr. Jonas Tölke
Institut für Computeranwendungen im Bauwesen
TU Braunschweig

Modeling and Simulation of Multiphase flow with the Lattice Boltzmann Method on the Microscale

After an introduction to the generalized lattice Boltzmann (GLB) method and its applications to macroscopic flow problems, recent improvements and developments for the GLB and the efficient modeling of multiphase flow on the microscale are presented. Several simulations of multiphase flows through porous media including dynamic effects are given and discussed.

16:00 Uhr
Birgitte Eikemo
Haakon Haegland
Department of Mathematics
University of Bergen

A Discontinuous Galerkin Method for Computing Transport Flow in Porous Media" und "Streamline tracing on irregular grids

We consider a discontinuous Galerkin scheme for flow in heterogeneous media. By applying an optimal reordering algorithm, one does not need to assemble the full linear system and may compute the solution in an element-by-element fashion. We demonstrate the discontinuos Galerkin method and the prior reordering on a boundary value problem for time-of-flight. Streamline methods have shown to be effective for reservoir simulation. For a regular grid, it is common to use the semi-analytical Pollock's method to obtain streamlines and time-of-flight coordinates (TOF). The usual way of handling irregular grids is by trilinear transformation of each grid cell to a unit cube together with a linear flux interpolation scaled by the Jacobian. The flux interpolation allows for fast integration of streamlines, but is inaccurate even for uniform flow. To improve the tracing accuracy, we introduce a new interpolation method, which we call corner velocity interpolation. Instead of interpolating the velocity field based on discrete fluxes at cell edges, the new method interpolates directly from reconstructed point velocities given at the corner points in the grid. This allows for reproduction of uniform flow, and eliminates the influence of cell geometries on the velocity field. Numerical examples demonstrate that the new method is more accurate than the standard tracing methods.

16:00 Uhr
Steffen Ochs
Lehrstuhl für Hydromechanik und Hydrosystemmodellierung

Steam injection into saturated porous media - process analysis including experimental and numerical investigations

The extensive use of artificial chemicals in industry and the lack of understanding their potential threat to the environment and to human health resulted in substantial soil and groundwater contaminations during the 20th century in many industrialized areas. Sites contaminated by dense non-aqueous phase liquids (DNAPL's) turned out to be problematic. The fact that DNAPL's have a higher density than water enables them to migrate below the ground water table causing extensive contaminations in the saturated zone. Conventional remediation techniques show major difficulties in the remediation of DNAPL and induced the development of innovative remediation techniques for such sites. One of the most promising is the injection of steam into the subsurface. This technique has been successfully applied to the remediation of DNAPL contaminations in the unsaturated zone. Today, the application of steam injection for the treatment of contaminations in the saturated zone is in the focus of research interest. Although the physical processes elapsing during steam injection are basically the same either in the saturated and unsaturated zone, there are distinct differences in their relevancy. In the talk the results from experimental and numerical investigations on the spreading behavior of steam fronts in saturated porous media will be presented and discussed.

16:00 Uhr
Dr. Ulrich Lang
Ingenieurgesellschaft Prof. Kobus und Partner GmbH

Grundwassermodell für Stuttgart 21, Prognosewerkzeug zur fachlichen Begleitung der Baumaßnahmen

Um die wasserwirtschaftlichen Auswirkungen von Baumaßnahmen im Grundwasser beurteilen zu können, werden geeignete Werkzeuge benötigt, die die aktuellen und zukünftigen Verhältnisse im Grundwasserleiter abgesichert quantifizieren. Für das Projekt Stuttgart 21 wurden deshalb im Vorfeld der Planfeststellung ein Grundwassermodell erstellt, mit dem die Auswirkungen der geplanten Baumaßnahme auf das Grundwasserleitersystem in Stuttgart und Bad Cannstatt mit dem Neckartal prognostiziert wurden. Das Modell wurde zunächst entsprechend dem hydrogeologischen Systemmodell des Amtes für Umweltschutz der Stadt Stuttgart aufgebaut und für stationäre Verhältnisse kalibriert. Für die stationäre Strömungssituation bei mittleren hydrologischen Verhältnissen erfolgten dann Prognosen zu den wasserwirtschaftlichen Auswirkungen. Da die Ergebnisse von Grundwassermodellen nicht nur vor und während der Planungsphase unabdingbar sind, wurde das Modellinstrumentarium der Planfeststellung auch hinsichtlich der Berücksichtigung instationärer hydrologischer Prozesse erweitert, mit dem eine baubegleitende Modellierung und zeitnahe Überprüfung der in den wasserrechtlichen Genehmigungen formulierten Auflagen möglich ist.

16:00 Uhr
Professor Dani Or
Laboratory of Soil & Environmental Physics (LASEP)
School of Architectural, Civil and Environmental Engineering (ENAC)
Ecole Polytechnique Federale de Lausanne (EPFL)

Textural Contrasts, Pore Size Distribution, and Characteristic Lengths Affecting Evaporation Rates from Porous Media – Measurements and Models

Evaporation from soil and other porous materials plays an important role in the hydrologic cycle as well as in a wide range of engineering applications. Dynamics of evaporative drying rates reflect complex interplay between soil pore space, transport properties and boundary conditions. An initially high drying rate induced by atmospheric or air flow over wet soil surface, may gradually decrease as mass flow between a receding drying front becomes limiting. Subsequent water would then be driven by vapor diffusion through soil pores at significantly slower rates. Theoretical and experimental results indicate that the depth of the drying front depth at which a transition from mass flow (high) to diffusion controlled (slow) evaporation takes place, is related to pore size distribution of a homogeneous porous medium, and to presence (and nature) of textural discontinuities within heterogeneous media. Dual and multi-capillary models are used to describe the competing forces and the origins of dominant characteristic lengths for evaporation. Measurements of drying front position and morphology within sand-filled Hele-Shaw cells were made with neutron transmission technique. New insights concerning water content distribution new the evaporating surface and dynamics of drying front in different coarse-textured materials are compared with theoretical predictions. The extent of polydispersity of pore sizes (either as pore size distribution, textural contrasts, or roughness within pore spaces) is key to sustaining high (and constant) evaporation rates via mass flow, and to determining length and time scales for abrupt changes in evaporation characteristics.

16:00 Uhr
Dr.-Ing. Holger Class
Lehrstuhl für Hydromechanik und Hydrosystemmodellierung

Models for Non-Isothermal Compositional Gas-Liquid Flow and Transport in Porous Media

The presentation covers a range of applications for non-isothermal compositional gas-liquid multiphase systems in the subsurface and in fuel-cells. The basic modeling concepts for multiphase flow systems in porous media will be briefly introduced and specific adaptions of the concepts to the individual type of applications are discussed. The complexity of the models has to be adapted to the problem and it may be useful in some cases to distinguish different time-scales where the processes can be described with models of different complexity.