Project, Bachelor and Master theses

The Chair of Fluid Mechanics offers different opportunities for students, graduates and students who are about to take their diploma, to assist in the education and research field.

Contact for numerical theses: Dr.-Ing. M. Meinke

Contact for experimental theses: Dr.-Ing. M. Klaas

Even in case there are no study, diploma, master, bachelor or project theses listed below, do not hesitate to contact the persons listed above.

Offered bachelor theses:

TopicDownload
Linear Waves incident to a Cone in Hypersonic Flow---
In this Bachelor/Masterthesis the response of the boundary layer of a 30deg half-angle cone to incident linear waves, i.e. fast acoustic and entropy waves, is investigated. Currently an unstructured flow solver using cartesian meshes is used to simulate the problem. In this work, the problem is investigated using a newly implemented structured solver. Your tasks: *Grid generation *Implementation of boundary conditions *Evaluation of the boundary layer response *Comparison with the results obtained by the unstructured flow solver Your Skills: *Linux *c++ *Matlab *Fluid Mechanics I&II (mandatory)
Topics in computational aeroacoustics---
Within our multiphysics simulation framework ZFS, we have a solver for computational aeroacoustics. Here we follow a hybrid approach to acoustics simulation: first, the flow field is obtained with our flow solver. Second, acoustic source terms are extracted, which are then used in our acoustics solver that uses the acoustic perturbation equations. If you are interested, please let me know - usually it is possible to find a topic that suits your ideas and our needs at the same time.
Separation control with air-jet vortex generators in a shock-wave / turbulent boundary layer interactionDownload
Flow fields around high speed vehicles are characterised by frequent occurrence of shock wave / boundary layer interactions. A strong shock wave imposes a large adverse pressure gradient on the boundary layer and can induce large scale separation. This interaction can lead to high local fluctuating pressure and thermal loads detrimental to the vehicle structure. Hence, effective control of these phenomena is necessary for cheaper and more efficient air and space transportation. A promising approach is based on the injection of air jets into the boundary layer. The streamwise vortices generated by these air-jets redistribute the momentum within the boundary layer, making it more resistant to separation. The effectiveness of air-jet vortex generators in mitigating flow separation has been verified in subsonic, transonic and supersonic flow conditions. However, further studies are essential to understand the underlying governing mechanism. In the framework of this proposed thesis, state-of-the-art experimental techniques will be employed to study the influence of air-jet vortex generators on shock wave / turbulent boundary layer interactions.
Wall-shear stress measurements of a turbulent wavy channel flow---
The Micro Pillar shear-stress sensor is designed for the measurement of the wall-shear stress distribution at high spatial and temporal resolution. It consists of an array of flexible cylinders flushmounted to the surface, protruding into the viscous sublayer and bending as a result of the fluid forces. The material of the cylinder is PDMS silicone such that the sensor has high elasticity, and the spheres on top of the pillars enable them to be optically detected. In the measurement, the pillars are to be mounted on four different positions of a sinusoidal surface, in order to study the influence of pressure-gradient on the wall-shear stress. The measurements will be carried in the wind-tunnel shown in the figure. The work of the students: - Fabrication of the sensors using silicone and casting molds - (bonus) Construction using CAD software (i.e. Inventor/CATIA) and communicate with workshop - Assistance during the measurement - Basic post-processing of measurement data Requirements: - Basic understanding of Fluid Dynamics - Capability in doing practical work - Thesis written in English - (bonus) CAD software (Inventor/CATIA) Beginning: From now on
Separation control in a hypersonic shock wave / turbulent boundary layer interaction using air-jet vortex generatorsDownload
Flow field around hypersonic vehicles are typically characterised by frequent occurrence of shock wave / boundary layer interactions. A strong shock wave imposes a large adverse pressure gradient on the boundary layer and can induce large scale separation. This interaction is quite detrimental in nature and can lead to high fluctuating pressure and thermal loads on the surface. Hence, proper control of this interaction is necessary for cheaper and more efficient air and space transportation. A promising approach for control follows injection of air jets into the cross flow to alter the incoming boundary layer characteristics favourably. The streamwise vortices generated by these air-jets redistributed the momentum within the boundary layer, making it more resistant to separation. The effectiveness of air-jet vortex generators in mitigating flow separation has already been verified in subsonic, transonic and supersonic flow conditions. An experimental investigation was carried out to study the influence of air-jet vortex generators on a hypersonic shock wave / turbulent boundary layer interactions, the results of which will be analysed in the context of this thesis.
Topics in discontinuous Galerkin methods---
Our multiphysics simulation framework ZFS has a built-in solver based on the discontinuous Galerkin method. On this solver there are numerous opportunities for Bachelor/Master theses or Projektarbeiten. If you are interested, please let me know - usually it is possible to find a topic that suits your ideas and our needs at the same time.
Aerodynamic parameters of speed skydiving---

Offered master theses:

TopicDownload
Numerische Analyse partikelbeladener turbulenter StrömungenDownload
Fast alle Strömungen, die in der Umwelt und Technik vorkommen, sind turbulent. Jedoch ist bereits die numerische Simulation einphasiger turbulenter Strömungen aufwendig, wobei es viele erfolgreiche Modellierungsansätze gibt. Eine noch größere Herausforderung besteht hingegen in der numerischen Analyse partikelbeladener turbulenter Strömungen. Trotz ihrer hohen Relevanz in Umwelt und Technik, sind vorhandene Modelle nur für vereinfachte Bedingungen gültig und eine Validierung steht oft noch aus. Ein wichtiger Anwendungsfall ist die numerische Auslegung einer Biomasse-Brennkammer. Dabei ist die Bestimmung der Aufheizraten, der Dynamik, und der turbulenten Durchmischung nicht-sphärischer Partikel entscheidend um den gesamten Verbrennungsprozess zuverlässig auszulegen. Die Generierung von hoch-aufgelösten Referenzdaten mit Hilfe von Simulationen und die Entwicklung von genauen Modellen für Anwender, sowie deren Validierung sind aktuelle Forschungsvorhaben, die am Aerodynamischen Institut intensiv verfolgt werden. Für dieses Projekt sind wir auf der Suche nach motivierten Masterarbeitern.
Topics in computational aeroacoustics---
Within our multiphysics simulation framework ZFS, we have a solver for computational aeroacoustics. Here we follow a hybrid approach to acoustics simulation: first, the flow field is obtained with our flow solver. Second, acoustic source terms are extracted, which are then used in our acoustics solver that uses the acoustic perturbation equations. If you are interested, please let me know - usually it is possible to find a topic that suits your ideas and our needs at the same time.
Porting a Lattice-Boltzmann Flow Solver to GPU---
The in-house software ZFS is a modular framework for the simulation of complex flows. One of the modules uses a Lattice-Boltzmann Method (LBM) to solve for the governing equations of flows. The LBM-code is massively parallelized and uses the Message Passing Interface (MPI) for inter-process communication and OpenMP for shared memory parallelization. The trend in High Performance Computing (HPC), however induces to use another level of parallelization by porting code to accelerators like NVIDIA GPUs or Intel Xeon Phis / Knights Landing. It is the aim of this thesis to port the existing LBM module of ZFS to an NVIDIA GPU and to investigate the performance gain obtainable by such an approach. The student will not only prepare a GPU implementation of the computational kernel but will also investigate the effort to transfer data to and from the GPU and the capability to hide the communication with other MPI processes and with the GPU behind the computation that is ideally balanced between both CPU and GPU.
Masterarbeiten im Bereich der WindenergieDownload

Im Rahmen unterschiedlicher For­schungsvorhaben wird am Aerodynamischen Institut der RWTH Aachen neben der Aerodynamik das Betriebsverhalten von Horizontal-, sowie Vertikalachswindenergieanlagen untersucht. Um zukünftigen Problem- und Fragestellungen effizient begegnen zu können, werden die hierfür verwendeten numerischen Methoden stetig weiterentwickelt.

Hierbei besteht die Möglichkeit im Rahmen verschiedener numerischer Abschlussarbeiten einen interessanten Einblick in aktuelle und zukünftige Fragestellungen aus dem Bereich der Windenergie zu erhalten.

Bei Interesse freuen wir uns über eine kurze Mail von Ihnen, um anschließend im persönlichen Gespräch die aktuell verfügbaren Themen für eine Abschlussarbeit zu besprechen.

Separation control with air-jet vortex generators in a shock-wave / turbulent boundary layer interactionDownload
Flow fields around high speed vehicles are characterised by frequent occurrence of shock wave / boundary layer interactions. A strong shock wave imposes a large adverse pressure gradient on the boundary layer and can induce large scale separation. This interaction can lead to high local fluctuating pressure and thermal loads detrimental to the vehicle structure. Hence, effective control of these phenomena is necessary for cheaper and more efficient air and space transportation. A promising approach is based on the injection of air jets into the boundary layer. The streamwise vortices generated by these air-jets redistribute the momentum within the boundary layer, making it more resistant to separation. The effectiveness of air-jet vortex generators in mitigating flow separation has been verified in subsonic, transonic and supersonic flow conditions. However, further studies are essential to understand the underlying governing mechanism. In the framework of this proposed thesis, state-of-the-art experimental techniques will be employed to study the influence of air-jet vortex generators on shock wave / turbulent boundary layer interactions.
Wall-shear stress measurements of a turbulent wavy channel flow---
The Micro Pillar shear-stress sensor is designed for the measurement of the wall-shear stress distribution at high spatial and temporal resolution. It consists of an array of flexible cylinders flushmounted to the surface, protruding into the viscous sublayer and bending as a result of the fluid forces. The material of the cylinder is PDMS silicone such that the sensor has high elasticity, and the spheres on top of the pillars enable them to be optically detected. In the measurement, the pillars are to be mounted on four different positions of a sinusoidal surface, in order to study the influence of pressure-gradient on the wall-shear stress.

The work of the students:
- Fabrication of the sensors using silicone and casting molds
- (bonus) Construction using CAD software (i.e. Inventor/CATIA) and communicate with workshop
- Assistance during the measurement
- Basic post-processing of measurement data

Requirements:
- Basic understanding of Fluid Dynamics
- Capability in doing practical work
- Thesis written in English
- (bonus) CAD software (Inventor/CATIA)

Beginning:
From now on

Please contact:
Frau Yiou Liu,
Aerodynamisches Institut, Raum 302
Wüllnerstr. 5a,
52062 Aachen
Email: y.liu@aia.rwth-aachen.de
Phone: +49-(0)241/80-90405
Separation control in a hypersonic shock wave / turbulent boundary layer interaction using air-jet vortex generatorsDownload
Flow field around hypersonic vehicles are typically characterised by frequent occurrence of shock wave / boundary layer interactions. A strong shock wave imposes a large adverse pressure gradient on the boundary layer and can induce large scale separation. This interaction is quite detrimental in nature and can lead to high fluctuating pressure and thermal loads on the surface. Hence, proper control of this interaction is necessary for cheaper and more efficient air and space transportation. A promising approach for control follows injection of air jets into the cross flow to alter the incoming boundary layer characteristics favourably. The streamwise vortices generated by these air-jets redistributed the momentum within the boundary layer, making it more resistant to separation. The effectiveness of air-jet vortex generators in mitigating flow separation has already been verified in subsonic, transonic and supersonic flow conditions. An experimental investigation was carried out to study the influence of air-jet vortex generators on a hypersonic shock wave / turbulent boundary layer interactions, the results of which will be analysed in the context of this thesis.
Aeroakustische Simulation des Rotorblattlärms von WindenergieanlagenDownload
Die Windenergie stellt in der Klimapolitik einen strategischen Baustein in der Energiewende dar. Im Gegensatz zu konventionellen Energieträgern ist die Leistungsdichte der Windenergie jedoch deutlich niedriger, was sich in einem hohen Flächenbedarf äußert. Neue gesetzliche Vorgaben, wie z.B. die Erhöhung des Mindestabstands von Windenergieanlagen zu bewohnten Gebieten, führen dazu, dass die für die Windenergie wirtschaftlich nutzbare Fläche schrumpft. Ein Grund für die Erhöhung des Mindestabstands ist die Lärmemission von Windenergieanlagen.

In verschiedenen Forschungsvorhaben werden am Aerodynamischen Institut der RWTH Aachen unterschiedliche Methoden für die aerodynamische Simulation von Windenergieanlagen entwickelt. Im Rahmen einer Masterarbeit soll die bestehende Simulationsumgebung um den Faktor des aeroakustischen Lärms, der von den Rotorblättern ausgeht, erweitert werden. Hierfür sollen geeignete semiempirische Modelle identifiziert, implementiert und bewertet werden.
Topics in discontinuous Galerkin methods---
Our multiphysics simulation framework ZFS has a built-in solver based on the discontinuous Galerkin method. On this solver there are numerous opportunities for Bachelor/Master theses or Projektarbeiten. If you are interested, please let me know - usually it is possible to find a topic that suits your ideas and our needs at the same time.
Coupling Structure and Flow Solvers for the Simulation of Fluid-Structure Interaction---
Nowadays, it becomes more and more important to accurately solve multi-physics problems by means of numerical simulations. This often requires to tightly couple different kinds of solvers that are responsible for the simulation of the different physics. This thesis should cover the direct coupling of a Lattice-Boltzmann flow solver and a structure solver to handle for Fluid-Structure Interaction (FSI) problems. Therefore, the student shall either integrate an existing structure solver into the in-house flow solver ZFS or use coupling libraries such as OpenPalm for the direct communication between an existing structure solver and ZFS. It is the aim to to have a working and efficient implementation at hand to simulate FSI problems in the field of bio-fluid mechanics on large scale supercomputers.
Workflow Automatization of a Nasal Cavity Flow Simulation Pipeline---
The pipeline of simulating the respiratory flow in the human nasal cavity consists of multiple steps, i.e., the extraction of a smooth and realistic geometry of the airway from computer tomography images, generation of a computational mesh, the simulation itself, and the post-processing of the simulation data. These steps commonly obey a dependency chain and are in general performed step-by-step. An automatization of this workflow by stringing together established best-practice methods and algorithms would be beneficial for the simulation end user as well as of importance for the integration in clinical applications in the long run. The student should evaluate the available tools and should automate the individual steps of the workflow as well as the data exchange between the consecutive steps to end up with a black box for the simulation of nasal cavity flows.
Aerodynamic parameters of speed skydiving---
Coupling a Level-Set Solver with a Lattice-Boltzmann Solver to Track Moving Boundaries---
Simulating moving geometries in a rapidly changing flow is a challenging tasks. A lot of technical, biomedical, and generic multi-physics applications necessitate to consider moving geometries to realistically simulate the corresponding physical processes. Different methods are commonly applied to track moving surfaces in a flow, e.g., the geometry is physically moved, the mesh is deformed by Arbitrary Lagrangian (ALE) approaches, or a pure Lagrangian ansatz is followed. Representing the geometry as a level-set, however, comes at a lower cost and allows to use the corresponding signed-distance function as a distance measure to the surface that can easily be used to refine the computational mesh around the moving object. Such a level-set approach is already implemented in the in-house flow solver ZFS for a finite volume method. The aim of this thesis is to couple the available level-set solver to the Lattice-Boltzmann flow solver in ZFS as well to enable easy surface tracking and dynamic refinement of the computational mesh.
Implementation of a Particle Evaporization Model for the Numerical Analysis of Allicin Deposition in the Human Airways---
Allicin is a cytotoxical product that might be capable of treating lung diseases like infections by streptococci. However, it is not well understood how such a treatment should ideally look like, i.e., what the optimal dose of allicin is, how the temperature influences its evaporization, and where the drug deposits in the human lung to take effect. Therefore, numerical simulations using a Euler-Lagrangian approach for the two-phase flow that accompany an experiment performed at the Institute of Aerodynamics are planned. To perform such simulations the available Lattice-Boltzmann flow solver and the Lagrangian particle solver need to be extended to account for particle evaporization. As such, a model for the evaporization including particle shrinkage as well as source-term definitions for a passive scalar are to be implemented by the student. The results of subsequent simulations should be juxtaposed to the corresponding experimental findings and a statistical analysis of the deposition and evaporization behavior should be performed.