Rainer Helmig, Department of Hydromechanics and Modelling of Hydrosystems Head, University of Stuttgart, Germany

Hosted by Shibo Wang

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Prof. Rainer Helmig is head of the Department of Hydromechanics and Modelling of Hydrosystems in the Faculty of Civil and Environmental Engineering at the University of Stuttgart, Germany. He gained his doctoral degree from the University of Hannover in 1993 and an advanced research degree (Habilitation) from the University of Stuttgart in 1997. In 1995, he was awarded the renowned “Dresdner Grundwasserforschungspreis” for his doctoral thesis on “Theory and numerics of multiphase flow through fractured porous media”. His habilitation thesis was published by Springer in the much-cited textbook “Multiphase flow and transport processes in the subsurface: A contribution to the modeling of hydrosystems”. From 1997 to 2000, Rainer Helmig held a professorship in “Computer Applications in Civil Engineering” at the Technical University of Braunschweig. Rainer Helmig was co-founder and, from 2009 to 2011, President of the International Society for Porous Media “InterPore”; he is spokesman of the International Research Training Group “NUPUS – Nonlinearities and upscaling in porous media” with partner universities in Delft, Utrecht, Eindhoven, Wageningen and Bergen, and he is a member of the Executive Board of Directors of the Cluster of Excellence Simulation Technology at the University of Stuttgart.  He is an elected member of the Heidelberg Academy of Sciences and Humanitiesand and he is on the editorial boards of a number of journals, such as Advances in Water Resources, and Computational Geosciences. Furthermore, he serves as Associate Editor for Water Resources Research.

Abstract

The subsurface is being increasingly utilised both as a resource and as an energy and waste repository. Historically, there have been few issues of concern related to competition between resources, with groundwater contamination being a notable exception. However, with increasing exploitation, resource conflicts are becoming increasingly common and complex. Current issues in this regard include, for example, the long-range impact of mechanical, chemical and thermal energy storage on groundwater resources, and the complex effects surrounding hydraulic fracturing in both geothermal and shale gas production. To analyse and predict the mutual influence of subsurface projects and their impact on groundwater reservoirs, advanced numerical models are necessary.

In general, these subsurface systems include processes of varying complexity occurring in different parts of the domain of interest. These processes mostly take place on different spatial and temporal scales. It is extremely challenging to model such systems in an adequate way, accounting for the spatially varying and scale-dependent character of these processes.

In this lecture, Rainer Helmig will:

• give an overview of possible utilisation conflicts in subsurface systems and of how  the groundwater is affected;
• review several model coupling concepts with a focus on the author’s work in this field. The concepts are divided into temporal and spatial coupling concepts, where the latter are sub-divided into multi-process, multi-scale, multi-dimensional, and multi-compartment coupling strategies;
• describe the fundamental properties and functions of a compositional multi-phase system in a porous medium. The basic multi-scale and multi-physics concepts are introduced and conservation laws formulated;
• explain the numerical solution procedures for both decoupled and coupled model formulations. Two applications of multi-physics and multi-scale algorithms will be presented and discussed;
• present a large-scale simulation that will show the general applicability of the modelling concepts of such complicated natural systems, especially the impact on the groundwater of simultaneously using geothermal energy and storing chemical and thermal energy. At the same time, he will show that such real large-scale systems provide a good environment for balancing the efficiency potential and possible weaknesses of the approaches discussed.