The energy transition has created a great need for understanding the physical phenomena occurring at electrodes, in systems like electrolysers, batteries, fuel cells or redox-flow batteries. So far, the three-dimensional effects resulting from the interaction of the electrode surface and the ions in the electrolyte are not sufficiently modeled or simulated - generating opportunities for further enhancing efficiency and power density. The present project aims at deriving a strategy for conducting such simulations based on the Nernst-Planck-Navier-Stokes system and then implementing the Nernst-Planck equations in an in-house code. (This code is very similar to the Matlab code developed in class „Numerics and Flow Simulation“).

If interested, please contact Prof. Dr. Andreas Kempf (andreas.kempf@uni-due.de)

Chemical reactions in the liquid phase, in stirred reactors or flow reactor systems, depend on the (turbulent) mixing of the flow - during stirring or as a result of the reactor geometry. Up to very recently, it was almost impossible to simulate this mixing, due to excessive compute time requirements. The present project will aim at applying a novel, efficient numerical technique to such problems, will work out its suitability, and determine the effect it can have on the results. Highly detailed simulations, ideally conducted on large super-computers, will be sought, processed and (potentially) published in a learned journal.

If interested, please contact Prof. Dr.Andreas Kempf (andreas.kempf@uni-due.de)

In a previous project, it was demonstrated that Artificial Neural Networks can be trained to predict the fluid flow around obstacles. The work was published in a journal but not pursued any further. The present project would aim to pick up this problem and to address a key issue that has remained - the fact that the continuity equation was not always satisfied. The new project would extend the previous work and attempt to develop a formulation that can also satisfy the continuity equation (conservation of mass), perhaps be training stream/potential functions, or based on a rotation-formulation.

If interested, please contact Prof. Dr.Andreas Kempf(andreas.kempf@uni-due.de)

Recent, very large simulations conducted at the chair, have lead to the observation of a new fluid-mechanical phenomenon - the formation of jets in detonations. There is speculation that these jets, in fact, lead to the knock-damage that is observed in engines. The present project will set up highly resolved simulations at relevant conditions and introduce a wall at the location of the jet. The resulting pressures and conditions must be monitored (in time) and evaluated. Ideally, these conditions will then be applied for a (plastic) simulation of relevant aluminium alloys to test if such a jet can explain the damage patterns that are observed.

If interested, please contact Prof. Dr.Andreas Kempf (andreas.kempf@uni-due.de)

Ammonia combustion has attracted significant interest due to its potential as a clean energy source, especially in the context of de-carbonization efforts. Understanding the complex dynamics of ammonia flames requires advanced computational techniques. This is particularly important due to the inherent challenges in modeling ammonia combustion, such as its low laminar flame speed and large and complex chemistry with wide range of time-scales.

The present project aims at the development of computer models and simulation tools for modeling the combustion of Ammonia. The project will involve the improvement of a numerical framework, the running of simulation, and the development of better reaction and transport models. Simulations will be conducted using the group’s in-house code PsiPhi, applying Servers and Clusters to provide the necessary computational power.

The project would necessitate a strong background in mathematics, numerics and fluid dynamics. If interested, please contact Prof. Dr.Andreas Kempf (andreas.kempf@uni-due.de) or Parsa Ghofrani (parsa.ghofrani@uni-due.de).

The utilization of iron powder in combustion processes presents a way to advance decarbonization initiatives by offering a sustainable alternative to conventional coal-based applications. Indeed, the reaction between iron and oxygen results in the formation of iron oxide without emitting any harmful emissions. The resulting iron oxide particles could be reduced to iron particles to close this energy cycle and use iron as a renewable energy source. Nevertheless, during the oxidation of iron powder, a certain amount of metals (iron or iron-oxide) is lost due to evaporation and the formation of nanoparticles, which requires further understanding and optimization through modeling and simulations.

The present project aims to develop sub-models for modeling the formation of nanoparticles in the process of iron powder combustion, based on detailed large eddy simulations. The project will involve improving a numerical framework, running simulations, and developing better reaction and transport models.

The project would necessitate a strong background in mathematics, numerics and fluid dynamics. If interested, please contact Prof. Dr.Andreas Kempf (andreas.kempf@uni-due.de) or Parsa Ghofrani (parsa.ghofrani@uni-due.de).

The detection of Hydrogen flames is a prerequisite for safety considerations in the ever-growing hydrogen (H2) energy systems. Its nearly invisible pale blue colour, especially in daylight, and low radiant heat that is usually only detectable very close to the flame, call for a reliable detection system to aid in effective safety control features such as shut-down, alarm activation, ventilation activation (when needed) and so on.

In this project, the concept of beam bending that is similar to the schlieren or background oriented schlieren (BOS) methods is to be utilised for the design of an optical detection system. The changes in refractive index within a reacting gas (flame) will bend light rays. The deflection of the light rays can be measured either by imaging a background pattern behind the combusting flow, or by aligning a light emitter and detector on opposite sides of the volume of interest. In the first phase, a weak laser pointer (low enough energy to prevent damage to the sensor) and a surveillance camera will be positioned around a flame for measurements to test the concept. Additionally, the existing BOS method of the group will be utilised to measure deflections on a background pattern behind the flame using a second camera. The two methods should be tested in terms of applicability and sensitivity.

The candidate must have a good grasp of MATLAB and the capability to perform optical experiments in the lab. Additionally, C programming experience is considered advantageous. The results of this work can potentially be published in a peer-reviewed journal with international recognition.

​For further information please contact(khadijeh.mohri@uni-due.de)

The mixing of hydrogen gas with air or other gases is of great importance for energy- and process-applications but also for studies on hydrogen safety. Research on laser-diagnostics has lead to elegant non-intrusive techniques for analyzing mixing, based on tracer molecules. These techniques have been established for gases with Schmidt- or Prandtl-numbers near unity, but the very high diffusivity of hydrogen may limit the suitability of such diagnostics. This Master’s or Bachelor’s project aims to conduct Direct Numerical Simulations (DNS) of hydrogen mixing in air, including an acetone tracer that would be applied to an experiment. The aim of the project is to establish the conditions, length and time-scales where an (organic) tracer is suitable for studying hydrogen mixing, and where it is not. Simulations will be conducted using the group’s in-house code PsiPhi, applying Servers and Clusters to provide the necessary computational power.

If interested, please contact Prof. Dr. Andreas Kempf (andreas.kempf@uni-due.de)

Bicycles (Road, Triathlon and TT) are now designed with aerodynamics in mind. One aspect that is much discussed (and rarely analysed in detail) is the aerodynamic drag generated by the wheels. Likely sources from a single wheel are the wakes of the leading rim and the trailing tire, the wakes of the advancing spokes, the roughness of the advancing tire (at its highest point) but also complex vortex systems generated by the rotating wheel. This Master’s project will aim at simulating the flow around a rotating wheel in detail, analyzing the flow-fields and the sources of drag, and possibly investigate (known) remedies - like higher and wider rim profiles, different tire profiles, or even the use of (aerodynamic!) mud-guards. Further, optional topics include the interaction of the wheel with the fork or the effects of the braking system on drag.

If interested, please contact Prof. Dr. Andreas Kempf (andreas.kempf@uni-due.de)

Bunsen Flames have been used for over one hundred years, and they have been studied for almost as long. A simple theory assumes an unperturbed flow field upstream of the flame and an (almost) unperturbed flow filed downstream. As a result of this simple flow field, Bunsen flames can be used to measure the laminar flame speed. Unfortunately, precise measurements cannot neglect the details of the flow-field, and neither can they neglect the curvature (at least in circumferential direction) of the flame. To improve the insight in such a flame, and the implications on the measurements of laminar flame speed, a Master’s project shall be conducted, simulating the laminar flow field in detail, combined with detailed combustion simulations by solving a suitable reaction mechanism. If possible, the effects of differential transport (due to the high diffusivity of hydrogen) should also be considered. The work will be conducted with OpenFOAM, a well established, powerful CFD-toolbox for which various extensions have been developed at the chair of fluid dynamics.

If interested, please contact Prof. Dr. Andreas Kempf (andreas.kempf@uni-due.de) or Prof. Wlokas (i.wlokas@uni-due.de).

Town planners, architects and councils require information on the wind-field, turbulence characteristics and pollutant transport throughout townscapes. Unfortunately, detailed wind-speed measurements, at many points and with many repetitions, are laborious, time-consuming, costly and often not practical. The present project aims to explore the idea of using a camera drone for measuring the wind speed with high temporal resolution, including gusts and turbulence. For this project, a camera drone must be identified that features a location holding feature, and which provides access to the data of the flight-control computer. This would permit to extract power settings, headings and inclinations, enabling to eventually extract data that permits to deduce the wind speed. In the main phase of the project, methods for computing the wind-speed (and its evaluation in time) shall be explored, combined with statistical methods for extracting time-averaged flow-field data and statistics on turbulence.

If interested, please contact Prof. Dr. Andreas Kempf (andreas.kempf@uni-due.de).

Elektrodes in batteries, fuel cells or chemical reactors are normally micro-structured, leading to a complex, inhomogeneous flow of ions in the electrolyte. The present projects aims to develop, test and validate a modeling framework for simulating transport near and in such electrodes. A general interest in computer programming and mathematical modeling is expected, a reasonable background in the relevant subjects is required.

If interested, please contact Prof. Dr. Andreas Kempf (andreas.kempf@uni-due.de)

Many engineers work on the reduction of carbon emissions by improving efficiency or by „decarbonization“, trying to substitute fossil fuels by other means. Unfortunately, such work falls short of looking at the „bigger picture“ - where changes in life-style, modes of transport, fuel consumption, entertainment and the way we work promise much greater savings in emissions. However, such changes would introduce enormous side-effects that cannot be predicted - largely due to highly non-linear interactions and complex couplings between the „players“. The present project aims at developing a flexible framework for general systems modeling, based on an agent model, to enable estimates of the impact of certain changes in lifestyle on carbon emissions and the economy.

This project can be considered „blue sky research“ and multiple students can work on it in parallel. A general interest in computer programming and mathematical modeling is expected, a reasonable background in the relevant subjects is required.

If interested, please contact Prof. Dr. Andreas Kempf (andreas.kempf@uni-due.de)

(Road and track) cycling has evolved tremendously, with great gains achieved by optimizing aerodynamics. However, it is not really clear „what works and why“ and what can be considered a „placebo“, mainly making a rider feel faster. The project aims at studying chosen bicycle parts (and complete bicycles with riders) to assess which parts and which interactions have (significant) effects on overall drag and performance. CFD- imulations will be conducted in three dimensions and with moving grids. A good background in mathematics, numerics and fluid mechanics is expected, an interest in cycling would be beneficial.

If interested, please contact Prof. Dr. Andreas Kempf (andreas.kempf@uni-due.de)

Engine knock remains a little understood phenomenon and represents a major unsolved problem in the context of ICE (internal combustion engines). It prevents the use of an engines optimal state of load, thus lowering the efficiency of the engine. Pre-combustion knock (or super-knock, a local premature ignition) is especially dangerous, as it may result in the complete failure of the engine. The aim of this thesis is to numerically investigate the physics of knock for a detonation wave propagating at Chapman-Jouguet speed. This detonation wave exhibits an unstable wave front, including the stochastic appearance of high momentum jets, which need to be analyzed. The simulations will be carried out with in-house code PsiPhi, whereby the setup of this type of simulation must be implemented and suitable ways to post-process the data must be found.

The project is challenging and requires strong skills in the field of fluid dynamics, thermo dynamics, reaction kinetics and numerics (FORTRAN, Python). It will be only attempted with very good candidates or long term HiWis.

If interested, please contact Prof. Dr. Andreas Kempf (andreas.kempf@uni-due.de)

Low emission (lean premixed combustion) gas turbine engines are prone to thermo-accoustic instabilities that can lead to the destruction of engines, which must be avoided, necessitating a detailed understanding of the phenomenon from simulation. Such Large-Eddy Simulations will be conducted using the in-house code PsiPhi, which is suitable for efficient, massively parallel simulations on super-computers. Recent work by our research group has shown that the normal, linear treatment of wave-propagation may not be sufficient at high frequencies of the instability, and we aim to simulate the phenomenon at high pressure levels, where even (non-linear) shock waves may occur. The present project aims at analyzing the phenomenon and preparing further research into this new topic. The work will involve setting up simulations, processing and interpreting the data, and writing a suitable report. A short version of the thesis shall be turned into a research paper that can be submitted to an international journal. A suitable student will have a strong background in fluid mechanics, mathematics and computer programming, and will be open to learning about new phenomena. The present project can be conducted in collaboration with researchers from the Technical University of Munich (TUM). A HiWi job on related topics can be offered prior to the Master’s project, using a closely related software.

If interested, please contact Prof. Dr. Andreas Kempf (andreas.kempf@uni-due.de)