230502: Direct Numerical Simulation of Hydrogen and Tracer-Molecule (De-) Mixing in a Turbulent Flow

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. Kempf.  (andreas.kempf@uni-due.de)

221018: Bicycle Aerodynamics

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. Kempf.  (andreas.kempf@uni-due.de) or Dr. S.J. Baik (seung.baik@uni-due.de).

221017: Master Project: Flamespeed measurements in Bunsenburner

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. Kempf.  (andreas.kempf@uni-due.de) or Prof. Wlokas (i.wlokas@uni-due.de).

211214: Master Project: Image reconstruction from (blurred) movies

The project aims to reconstruct "sharp“ images from a series of blurred images (e.g. video). Applications include the identification of car registration plates from blurred (police or dash-cam) movies, "night shots“, or similar. The software will be based on Matlab (or similar toolboxes / libraries) and follow concepts developed for tomographic algorithms - in particular the evolutionary reconstruction approach.

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

211214: Master Project: Wind and turbulence measurements by (camera) drone

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. Kempf.  ( andreas.kempf@uni-due.de).

211115: Bachelor/Master Project: Optimisation of wall temperature modeling in numerical simulations

Gas turbines powered by hydrogen (or occasionally natural gas) will be an important part of the future power generation, filling the gaps of sustainable sources, e.g. solar and wind. Lean combustion is used to manage the balancing act of reducing emissions while conserving the efficiency of gas turbines. While effectively reducing emissions, these combustion conditions are prone to exhibit high-frequency thermoacoustic instabilities. These instabilities are pressure waves driven by a coupling of heat release and combustion chamber acoustics. Without mitigation efforts, the pressure fluctuations may damage the device and therefore limit the safe operating range. Previous research has shown that thermoacoustic instabilities react sensitive to changes in the temperature field in the combustion chamber. In this project, advanced methods for the simulation of wall temperatures shall be investigated to improve the accuracy of the temperature predictions in the combustion chamber. As a benchmark, reactive Large-Eddy-Simulations will be performed using the OpenFOAM framework.

We seek a highly qualified candidate and a good background of fluid dynamics is required. Previous experience with CFD simulations is beneficial.

For questions or to apply for the project, please contact M. Sc. Jonas Eigemann (jonas.eigemann [at] uni-due.de).

210824: Bachelor/Master Project: Numerical study of flames forming nanoparticles

The numerical prediction of nanoparticle requires adequate and precise models for the characterization of the turbulent behavior of the flame as well of the different phenomena involved in nanoparticle production. Direct Numerical Simulations (DNS), providing a full description of all the temporal and spatial scales, and Large Eddy Simulations (LES), resolving only the most energetic scales, have been used to investigate nanoparticle production in academic configurations. The aim of this project is to investigate different numerical simulations of reactive flows forming nanoparticles, which will help to clarify the turbulence-particle-dynamics interaction and will guide the modeling efforts. Our department is seeking for highly qualified candidates with a strong mathematical and programming background. The successful candidate will have access to our in-house code PsiPhi and will use OpenFOAM for the investigation of nanoparticles production in reactive cases. He/she will also profit of the presence of many experienced researchers, active collaborations with experts in the area of numerical modeling of nanoparticles production in reacting flows, and in massively-parallel DNS-LES from the Chair for Fluid Dynamics.

For further information please contact Dr. Luis Cifuentes (luis.cifuentes [at] uni-due.de) .

210823: (Ion-) flow modeling for electrodes and active surfaces

210822: Development of a parallel systems modeling framework focused on CO2 emission (reductions)

210821: Flow simulation of moving bicycles and bicycle parts

200127: Master's Project: Numerical Investigation of Engine Knock

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.

For further information please contact Prof. Andreas Kempf ( andreas.kempfi@uni-due.de ).

170605: Large-Eddy Simulation of non-linear Thermoaccoustics (HiWi/Master)

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.

Student projects related to tomography (experimental and computational).