Everything flows

# Multi-phase and Multi-physics Modelling

We are improving simulation of flow and transport processes in order to solve complex problems in technology and nature, and to give reliable prognoses.

### Understanding Flow and Transport

If you want to predict the weather, or understand how certain substances underground behave – for instance if you want to prevent the seepage of harmful substances into ground water – then you have to deal with the flow and transport processes of substances. Such processes are also at work in the human organism: medications have to be transported in our blood vessels and much more besides. In industry and development too flow and transport processes play an important role – here they are often even applied specifically. Such as in the case of what is known as the cw-value for the aerodynamic shape of cars.

Simulation of the exchange process between plants and soil underground to prevent landslides. Here various scales are considered.

### Outlook

Often, the investigation of flow and transport processes is intended to answer questions on events in the future. In order to enable the accurate prediction of flow and transport processes and possibly even their influence, simulations and mathematical models are the method of choice. The aim of the researchers from various disciplines in PN 5 is to make the methods used and thus also the predictions more reliable.

### Complex Modelling: Scales, Phases and Interfaces

Flow and transport processes often have to be examined in detail and also as a whole, so across several scales. The behaviour of the flows must be understood on the nano, micro, meso, and macro scales. So we have to carry out simulations in this field on several different scales. However, different conditions apply for the various scales. For each scale different physical and mathematical approximation methods are needed. These methods must each be combined in a suitable way depending on the application – a complex task for the simulation scientists. They have to describe how flows behave on the threshold to other states, so in the case of phase transitions. For instance upon change from a solid to a fluid aggregate state. Here what is known as multiphysical modelling is needed. We use this to try to combine together the right physical models in an appropriate way to answer such interface questions.

At the research facility for subsurface remediation (VEGAS) at the University of Stuttgart, experiments on flow and transport processes are carried out.

### No Reliable Simulation without Experiments

A model is particularly good if it corresponds to the results of experiments. That’s why we use data from experiments at many points in PN 5 to validate the models – this is the only way we can improve them. And if we manage with our models to predict the outcome of experiments then we can assume that we are on the right path to accurately describing flow and transport processes.

### Data and Informatics

Parameters and input variables are mutually dependent. Informatics helps to find out the extent of dependence and to avoid it using complex dependence relations. This creates a separate class of research challenges in informatics, which informatics experts in PN 5 tackle together with engineers and mathematicians.

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5-1
Theory and numerics of fracturing porous media

Project Coordinator: Prof. Dr.-Ing. Wolfgang Ehlers
Research Associate: Chenyi Luo
Institute of Applied Mechanics (CE)

5-2
Multi-scale multi-physics modelling of complex systems: efficient and robust models for large scale applications in porous media
Project Coordinator: Prof. Dr.-Ing. Rainer Helmig, apl. Prof. Bernd Flemisch
Research Associate:Martin Schneider
Institute for Modelling Hydraulic and Environmental Systems

5-3
3D Direct Numerical Simulations (DNS) of Heat and Mass Transfer of Multi-Component Droplets including Phase Change
Project Coordinator: Prof. Dr.-Ing. Bernhard Weigand
Research Associate: Karin Schlottke
Institute of Aerospace Thermodynamics

5-4
Explicit-implicit discontinuous Galerkion schemes for multi-phase flow
Project Coordinator: Prof. Dr. Claus-Dieter Munz
Research Associate: Serena Keller
Institute of Aerospace and Gas Dynamic

5-5
Large-scale arrival time statistics and risk assessment for transport in complex multi-scale formations
Project Coordinator: Prof. Dr.-Ing. Wolfgang Nowak
Research Associate: Sebastian Most
Institute for Modelling Hydraulic and Environmental Systems

5-6
Controlling Uncertainty in Fractured Porous Media
Project Coordinator: Prof. Dr. Christian Rohde
Research Associate: Markus Köppel
Institute of Applied Analysis and Numerical Simulation

5-7
Adaptive Higher Order DG Methods for Porous-Media Multi-Phase Flow with Strong Heterogeneities
Project Coordinator: Prof. Dr. Kunibert G. Siebert
Research Associate: Birane Kane
Institute for Modelling Hydraulic and Environmental Systems

5-8
Visualization of Flow and Fracture in Porous Media
Project Coordinator: Prof. Dr. Thomas Ertl
Research Associate: Michael Bussler
Institute of Visualisation and Interactive Systems

5-9
A numerical, adaptive approach for modelling parameter dependencies and uncertainties
Project Coordinator: JP Dr. Dirk Pflüger
Research Associate: Fabian Franzelin
Institute for Parallel and Distributed Systems

5-10 (completed)
Virtual Characterization of Permeable Materials
Project Coordinator: Prof. Dr.-Ing. Heinz Voggenreiter
Research Associate: Thomas Rothermel
Institute of Materials Reserach, Deutsches Zentrum für Luft- und Raumfahrt (DLR)

5-11
Quality assurance in numerical software frameworks at example of Dune / PDELab / DuMuX
Project Coordinator: Dr.-Ing. Rainer Helmig, apl. Prof. Bernd Flemisch
Research Associate: Nicolas Schwenck
Institute for Modelling Hydraulic and Environmental Systems

5-12
DUNE project
Project Coordinators: Prof. Dr. Kunibert G. Siebert, Prof. Dr. Christian Rohde
Research Associate: Martin Alkämper
Institute of Applied Analysis and Numerical Simulation

5-13
Verfification experiment
Project Coordinators: Dr.-Ing. Rainer Helmig, Prof. Dr.-Ing. Bernhard Weigand
Research Associate: Alexandros Terzis
Institute for Modelling Hydraulic and Environmental Systems, Institute of Aerospace Thermodynamics

5-14
Elliptic equations with stochastic Levy-field coefficients
Project Coordinator: JP Dr. Andrea Barth
Research Associate: Dr. Ilja Kröker
Institute of Applied Analysis and Numerical Simulation

5-15
Reduktion verfahrenstechnischer Multiskalen-Methoden mit Dünngitterbasierten adaptiven Approximationsmethoden
Project Coordinators: JP Dr. Dirk Pflüger, Prof. Dr.-Ing. Ulrich Nieken
Research Associate: Michael Rehme
Institute for Parallel and Distributed Systems, Institute of Chemical Process Engineering

5-assoziiert
Kopplung von Fluidik-Strukturmechanik- und Akustikberechnungen und deren skalierbare Umsetzung
Project Coordinator: Prof. Dr. Miriam Mehl
Research Associate: Florian Lindner
Institute for Parallel and Distributed Systems

• Engineering
• Mathematics
• Computer science

### Coordinators PN 5

apl. Prof. Dr. rer. nat.

Prof. Dr.-Ing.