Nowadays society strongly depends on its available resources and the long term stability of the surrounding ecosystem. Numerical modelling has become a general standard for evaluating past, current or future system states for a large number of applications supporting decision makers in proper management. In order to ensure the correct representation of the investigated processes and results of a simulation, verification examples (benchmarks), that are based on observation data or analytical solutions, are utilized to evaluate the numerical modelling tool.
In many parts of the world, groundwater is an important resource for freshwater. While it is not only limited in quantity, subsurface water bodies are often in danger of contamination from various natural or anthropogenic sources. Especially in arid regions, marine saltwater intrusion poses a major threat to groundwater aquifers which mostly are the exclusive source of freshwater in these dry climates. In contrast to common numerical groundwater modelling, density-driven flow and mass transport have to be considered as vital processes in the system and in scenario simulations for fresh-saltwater interactions.
In the beginning of this thesis, the capabilities of the modelling tool OpenGeoSys are verified with selected benchmarks to represent the relevant non-linear process coupling. Afterwards, variable-density application and process studies on different scales are presented. Application studies comprehend regional groundwater modelling of a coastal aquifer system extensively used for agricultural irrigation, as well as hydro-geological model development and parametrization. In two process studies, firstly, a novel method to model gelation of a solute in porous media is developed and verified on small scale laboratory observation data, and secondly, investigations of thermohaline double-diffusive Rayleigh regimes on medium scale are carried out.
With the growing world population and, thus, increasing pressure on non-renewable resources, intelligent management strategies intensify demand for potent simulation tools and development of novel methods. In that way, this thesis highlights not only OpenGeoSys’ potential of density-dependent process modelling, but the comprehensive importance of variable-density flow and transport processes connecting, both, avant-garde scientific research, and real-world application challenges.:Abstract
Zusammenfassung
Nomenclature
List of Figures
List of Tables
I Background and Fundamentals
1 Introduction
1.1 Motivation
1.2 Structure of the Thesis
1.3 Variable-Density Flow in Literature
2 Theory and Methods
2.1 Governing Equations
2.2 Fluid Properties
2.3 Modelling and Visualization Tools
3 Benchmarks
3.1 Steady-state Unconfined Groundwater Table
3.2 Theis Transient Pumping Test
3.3 Transient Saltwater Intrusion
3.4 Development of a Freshwater Lens
II Applications
4 Extended Inverse Distance Weighting Interpolation
4.1 Motivation
4.2 Extension of IDW Method
4.3 Artificial Test and Regional Scale Application
4.4 Summary and Conclusions
5 Modelling Transient Saltwater Intrusion
5.1 Background and Motivation
5.2 Methods and Model Setup
5.3 Simulation Results and Discussion
5.4 Summary, Conclusion and Outlook
6 Gelation of a Dense Fluid
6.1 Motivation
6.2 Methods and Model Setup
6.3 Results and Conclusions
7 Delineating Double-Diffusive Rayleigh Regimes
7.1 Background and Motivation
7.2 Methods and Model Setup
7.3 Results
7.4 Conclusions and Outlook
III Summary and Conclusions
8 Important Achievements
9 Conclusions and Outlook
Bibliography
Publications
Acknowledgements
Appendix
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:28302 |
| Date | 07 May 2014 |
| Creators | Walther, Marc |
| Contributors | Liedl, Rudolf, Kolditz, Olaf, Graf, Thomas, Schirmer, Mario, Technische Universität Dresden |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | doc-type:doctoralThesis, info:eu-repo/semantics/doctoralThesis, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
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