Are you looking for an opportunity to write your thesis in an international setting and with the right experts of your field of research? Thanks to our network, we can help you find supervision and a topic at one of our partner universities – NTNU in Trondheim, AAU in Aalborg, CUT in Cracow, DTU in Copenhagen, DCU in Dublin and TUB in Berlin.
Should you be interested in writing one of them, please get directly in contact with the respective department. If you are looking for financial support for your stay abroad, you can apply for our annually given NWN-scholarships, funded by the German Academic Exchange Service (DAAD). For more information, don’t hesitate to contact us.

Validation of a new measurement technique to characterise rise velocities and bubble sizes

Dublin City University

Master

Details

Supervisor: Yan Delauré and Post-Doctoral Researcher responsible for computational study
Department: Mechanical and Manufacturing Engineering, DCU Water Institute
Keywords:  microbubbles, mass transfer, surface tension, two-phase flow modelling/experimental analysis.
Time frame/ Semester: From September 2019 or February 2020 (flexible)

Project background

This MSc thesis will support an on-going project on the study of oxygen transfer efficiency in process aeration. Aeration tanks are often operated with diffusers generating coarse bubbles, which rise quickly and therefore reach the surface before releasing most of their oxygen to the water. The reduction of bubble sizes (<1mm) enhances surface to volume ratio as well as the residence time of bubbles in the tank, which are two key parameters for interfacial transfer. Experimental results on oxygen transfer have been obtained with aqueous solutions in the lab and with wastewater on site and an effective methodology for the characterisation of bubble sizes which relies on shadow sizing (visualisation method) has been validated. This method however will not be suitable for larger scale tank tests that are planned. An optical probe has been acquired and the aim of this thesis will be test the limits of this alternative measurement approach by comparing test results with the existing visualisation method. Once validated, the method will be used to characterise the bubbles velocity and sizes for a range of bubble generator. Results will be used to adapt correlations for oxygen transfer and bubble drag coefficients to be used in a parallel computational study of the process. It is expected that results will form part of a research publication.

Research focus

The MSc thesis will focus on the validation of a new measurement technique to characterise the rise velocities and bubble sizes (including bubble growth during its rise through the water column). These measurements are required to tune empirical parameters used in computational models based on Lagrangian approach to bubble tracking and simulation of oxygen transfer from bubbles to liquid. The student will conduct and process a series of tests with micro and millimetre scale bubble generators which have already been tested at DCU. Acoustic measurements will be compared with data extracted from visualisation studies. Of particular interest is the ability of the single point measurement to deal with extremes in bubble size. At the sub-millimeter scale the probe may fail to penetrate the interface due to increased surface tension and at the other end of the scale (with much larger bubbles), bubble shape assumptions made in the post-processing software may skew the results. The experimental set up will be modified to allow testing at both limits. The existing setup will allow testing with very small bubbles but not a mixture of large and small bubble. An air water pump will be connected and piping modified to make it possible to generate a broad range of multiphase flow mixtures at conditions similar to what can be expected from the full scale aerator from the industrial partner.

Student tasks

The student will be responsible for:

– Implementation and validation of size measurement technique under control ideal micro-bubble conditions
– Simultaneous characterisation of a bubble cloud and Dissolved Oxygen mixing.
– Comparison of oxygen transfer measurements with computational simulations (by Post-doctoral researcher) to assess significance of bubble growth on prediction accuracy

 

Design and development of a turbulent water channel for the study of drag over micro-textured surfaces

Dublin City University

Master

Details

Supervisor:  Dr Yan Delauré and PhD student responsible for turbulent water tunnel design/built
Department: Mechanical and Manufacturing Engineering, DCU Water Institute
Keywords:  Fluid Structure Interaction, PIV, Experimental flow analysis
Time frame/ Semester: From February 2020 (flexible)

Project background

A large scale collaborative project involving the Dublin City University Water Institute and an EU consortium of universities and SMES will aim to study the anti-fouling and drag reduction characteristics for a range of micro-textures applied over surfaces. The aim is to improve the performance both in terms of anti-fouling and hydrodynamic properties of tidal stream turbines. The EU project started in April 2019 and the proposed Masters’ thesis is intended to prepare the experimental part by completing both design, built and testing of a test section to incorporate to an existing design of a turbulent water tunnel. This test section will incorporate pressure measurement and allow for PIV measurement of the flow.

Research focus

Extensive research has been performed on the impact of various micro-structures on external fluid flow. Desirable effects have been documented, in particular drag mitigation (https://aip.scitation.org/doi/10.1063/1.4942474)  and reduction in rate of micro-organism settlements (https://pdfs.semanticscholar.org/6edc/466f0a7cdbfb4cd8e7149521bcd50fc5cde7.pdf). Experimental characterisation of both phenomena can be informed by a combination of pressure drop, friction stress and flow velocity characterisations. Our research will rely on the pressure and flow velocity measurements. This thesis will design the test section for our specific needs and characterise the flow achieved in terms of its turbulence structures. The primary aim is to replicate high Reynolds near zero pressure boundary layer flow over flat surfaces. Although part of the thesis is to make a contribution to the design effort, the core research will focus on the application of PIV to characterise the channel flow profile and its characteristics. The study will consider a range of flow velocities to suit the attachment strength of micro-organism to be studied and tests will be performed to confirm these conditions for a follow study of detachment of micro-organisms due to biofouling.

Student tasks

The student will be responsible for:

– Review of the literature to identify the attachment strengths of the two marine micro-organisms of interest and to determine the flow conditions to achieve in the test section (to be performed in collaboration with a PhD student studying the biofouling)
– Complete an existing design of the test section to allow for PIV characterisation
– Conduct experimental study of turbulent flow in test section under ideal flat plate conditions
– Extend study to include micro-structured surfaces if feasible within time of thesis

Experimental characterisation of flexible membrane dynamics due to Fluid Structure Interaction

Dublin City University

Master

Details

Supervisor:  Dr Yan Delauré and PhD student (former TU Berlin MSc. Student)
Department: Mechanical and Manufacturing Engineering, DCU Water Institute
Keywords:  Fluid Structure Interaction, DIC, PIV, Experimental flow analysis
Time frame/ Semester: From September 2019 or February 2020 (flexible)

Project background

An on-going collaborative project involving the Dublin City University Water Institute and Sulzer Pump Solutions Ireland aims to characterise the transport of flexible structures and their interaction with fixed and moving walls. The key objective is to develop and validate a computational tool capable of modelling the transport of flexible cloth like objects in centrifugal pumps.

Research focus

This MSc thesis is intended to support the experimental part of the research. Specific experimental techniques implemented to date include Digital Image Correlation and 3D planar Particle Image Velocimetry. The upgrade to stereoscopic PIV was recently completed by a MSc Student from TU Berlin. To date experiments have been performed to measure structural deformations due to forced motion in quiescent fluid. The aim of this thesis is to define, perform and analyse experiments to characterise the dynamics of a clamped and free flowing flexible structures in flowing fluid at moderate Reynolds Number. Two different materials and different thicknesses will be considered and both PIV and DIC will be used. The first part of the research will rely on an existing setup and water tunnel but in a second stage the feasibility of simultaneous PIV/DIC measurements will be investigated. The aim is to publish the research results as part of the overall validation.

Student tasks

The student will be responsible for:

– Uncertainty calculations for flow and structural deformation measurements
– Improved design of tunnel inlet and fixation system
– Experimental characterisation of flexible membrane FSI under range of conditions. Note that very little published research exists on this topic.
– Implementation and testing of simultaneous PIV/DIC measurements.

Water distribution modelling – estimation of water consumption and leakages based on smart water meter data

Norwegian University of Science and Technology

Master

Details

Supervisor: Marius M. Rokstad & Sveinung Sægrov (possible to suggest co-supervision from TU Berlin)
Department: Department of Civil and Environmental Engineering, Norwegian University of Science and Technology
Keywords: Smart water meters, leakage management, statistical analysis
Time frame/ Semester: January to June 2020 (spring semester)

Project Background

Trondheim kommune has ambitions to reduce the leakages in their water distribution system (WDS) from 28 to 20 %. In order to achieve this goal, considerable investments must be made, with regards to pipe rehabilitation, pressure management and leakage detection. However, it is also of paramount importance to have good estimates of the current water consumption, leakage level and minimum night flow in the system.

Trondheim has currently approximately 35 District Meter Areas (DMAs), but there is currently an ongoing project to increase the number of DMAs. Trondheim is also involved in a project where smart water meters (SWMs) are being tested. It is assumed that these developments will make it possible to obtain better estimates on the water consumption and loss. The use of advanced statistical analyses and artificial intelligence may also help make sense of such data.

Research focus:

Collection and (statistical) analysis of operational data from smart water meters and SCADA-systems, for estimation of water consumption and water loss parameters, and the variations in time and space for these parameters.

Student tasks:

Perform literature study on smart water meters, leakages, estimation of consumption and leakages
Collect data from Trondheim’s SWMs and SCADA system
Perform statistical analyses on collected data to get estimates of:
– Minimal night consumption and leakage level
– Water consumption, with variations in time and space
– Evaluation of results and assessment of the usefulness and potential for installing SWMs in Trondheim

Evaluation of the passive vortex flow regulator efficiency based on CFD modeling

Cracow University of Technology

Master

Details

Supervisor: Andrzej Mączałowski, Tomasz Siuta
Faculty of Environmental Engineering
Department: Hydraulics and Hydrology
Keywords: turbulent flow, ogee spillway, hydraulic jump, energy dissipation
Time frame/ Semester: From October 2019 (flexible)

Project background

Within an urban drainage network, it is usually necessary to regulate flow through the system to control the effects of storm surges. This could be realised by applying control devices in the critical nodes of the network, which allow divert storm surges to attach storage containers for later processing and to protect to not overload wastewater plant during storm occurrence. Many active and passive controllers have been developed, one of is the vortex flow control. This self-activating device relies on the properties of the vortex formed at a chamber of regulator and the outlet pipe to regulate the flow discharge magnitude. The hydraulic behavior of these devices is influenced by their geometry and orientation that contribute to substantial increase of flow resistance in the case of the high outflow discharge magnitudes occurring mainly during storm events.

Research focus

Capability of CFD modeling to capture bi-stable rating curve characteristics and turbulent vortex flow patterns within passive flow discharge regulator is investigated. The research focusses on the study of kinetic turbulent energy dissipation processes influenced by geometry and orientation of the regulator. The optimal grid resolution is searched for a given model of turbulence attached to RANS model. The pressure drop (negative pressure magnitude) and its influence on the rating curve function is also investigated. The rating curve validation will be done based on lab experiment.

Student tasks

Student will get access to perform lab experiment for the given example of the vortex flow regulator. Student will prepare geometric model and run numerical CFD model (based on the FLOW 3d program or other) of the flow through the vortex regulator for the different flow conditions. Rating curves obtained based on numerical modeling will be compared with observation data. Some optimal design geometric features of regulators will be pre-formulated.

CFD modeling of turbulent energy dissipation of the water flow discharged by the sluice gate within the downstream part of the channel under consideration of air entrainment process

Cracow University of Technology

Master

Details

Supervisor: Andrzej Mączałowski, Tomasz Siuta
Faculty of Environmental Engineering
Department: Hydraulics and Hydrology
Keywords: turbulent flow, ogee spillway, hydraulic jump, energy dissipation
Time frame/ Semester: From March 2019 (flexible)

Project background

The stilling basin is a basin (or part of the water channel) constructed to dissipate the energy of fast-flowing water (e.g., from a spillway or bottom outlet), and to protect the streambed from erosion. The turbulence and two-phase (air-water) flow processes (e.g. air concentration spatial and time variation) mainly contributes to dissipation of kinetic energy of the flow discharged by the sluice gate from the upstream storage. Different facilities are used to control such energy dissipation and protect dam or riverbed from erosion (e.g. baffles, sills, macro-roughness and others).

Research focus

The influence of air entrainment on turbulence intensity and impact of turbulence itself on the hydraulic jump characteristics is investigated.  Capability of CFD modeling to capture the most important features of turbulent flow like a kinetic energy dissipation, pressure and velocity distribution, shear stress in the boundary layer and air concentration field are studied with reference to the small-scale lab experiment.

Student tasks

Student will get access to perform the small-scale lab experiment for the given physical model of water storage discharged by the sluice gate into the channel with and without installed sill. Student will prepare and run numerical CFD model (based on the FLOW 3d program or other) of the hydraulic jump downstream of the sluice gate for the different flow condition. Results of numerical modeling will indicate zones of intense turbulent energy dissipation and will allow evaluating the impact of the sill on the energy dissipation efficiency. Next, these results will be compared with observation and some simplified measurements data.

CFD modeling of turbulent flow through the ogee spillway with reference to the small scale lab experiment

Cracow University of Technology

Master

Details

Faculty of Environmental Engineering

Supervisor: Andrzej Mączałowski, Tomasz Siuta
Department: Hydraulics and Hydrology
Keywords: turbulent flow, ogee spillway, hydraulic jump, energy dissipation
Time frame/Semester: From March 2019 (flexible)

Project background

A spillway is a structure used to provide the controlled release of flows from a dam or levee into a downstream area, typically the riverbed. Proper design and safe exploitation of hydraulic structures like an ogee spillway and a stilling basin require to take under consideration high spectrum of turbulent flow conditions (e.g. different forms of hydraulic jump) which may influence either flow discharge characteristic and erosion and cavitation damage intensity in some regions of spillway and water channel.

Research focus

Capability of CFD modeling to capture the most important features of turbulent flow like a kinetic energy dissipation, pressure and velocity distribution, shear stress in the boundary layer are studied with reference to the small scale lab experiment.

Student tasks

The student will get access to perform the small-scale lab experiment for the given ogee spillway physical model installed in water channel. He/she will prepare and run numerical CFD model (based on the FLOW 3d program or other) of the flow through the ogee spillway for the different flow condition. Results of numerical modeling will be compared with observation and some simplified measurements data.

Comparative analysis of river-water quality improvements in two rivers measured using the contingent valuation method

Cracow University of Technology

Master

Details

Supervisor: Tomasz Stypka
Department: Dept. of Environmental Engineering
Keywords: cvm, valuing water quality,
Time frame: Autumn semester 2019

Project background

Any rational decisions in the field of environmental management require analysis of the potential costs and benefits. Very often, these potential benefits or costs are difficult to be expressed in monetary terms. Improvement of river water quality is one of such benefits. The value of water quality depends on many factors including present water quality level, social awareness, standard of living and many others. Knowing the value of water quality can help decision makers responsible for the river and for the city development and knowing how this value change with standard of living can be an additional guideline.

Research focus

estimate the present water quality in local rivers in two towns, and the potential for improvements. Comparing the municipal approach to the river water quality. Estimating the value of river water quality in two towns. Contingent valuation method is probably the best approach for this task.

Student tasks

Gather information about the rivers flowing in two towns, there quality, social role and potential for water quality improvements. Prepare and conduct between two city dwellers an extensive polling, using mainly Internet, to estimate the value of water quality improvements. Conduct a comparative analysis of the obtained results.

Impact of the degree of sealing on the runoff in the urban catchment

Cracow University of Technology

Master

Details

Supervisor: Elżbieta Jarosińska, PhD
Faculty of Environmental Engineering
Department: Hydraulics and Hydrology
Keywords: Catchment, urban development, rainfall-runoff model, flood wave
Timeframe/Semester: Spring 2019 (March-June) or Autumn 2019

Description

Urbanisation and climate change have significant impact on disturbing the water balance in catchments. Uncontrolled urban development, increased land surface sealing and increasingly frequent heavy rainfall cause local floods called urban flooding. Short-duration intense rainfalls are responsible for the highest discharges in rain water drainage or combined sewage systems. For this reason, it is important to know the impact of the amount of rainfall and the degree of sealing on the runoff in urban catchments.

Project background

The purpose of this work is to characterise a flood wave (flood time, time to peak, time of falling wave, value of the peak of the runoff Qmax) for: 1) natural conditions in the catchment, 2) conditions of different sealing degree, 3) variable precipitation.

Research focus

The results of the work, derived from studies performed for various variable factors, are aimed at analysing the impact of individual factors on the flood waveforms obtained in modelling.

Student tasks

The student’s task will be to simulate the runoff in a catchment using the rainfall-runoff model and to compare flood waves obtained for various rainfall data, types of catchment area management and variable precipitation.

Analysis of the location of green roofs in the city on the example of Krakow

Cracow University of Technology

Master

Details

Supervisor: Bąk Joanna
Department: Environmental Engineering
Keywords: green roof, green infrastructure, heat island, rainwater management, LID
Time frame/ Semester: from March 2019

Project background

Green roofs are important for adapting cities to climate change. Their role in managing rainwater and reducing the effects of the urban heat island is particularly important. The scale of the positive effect in their application depends, however, on their location in the city (center/outskirts) and the number of such facilities in the immediate neighborhood. The sewerage system is also important (combined/separated) that supports the objects on which they are located.

Research focus

The aim of the research is to analyze the distribution of green roofs in Krakow due to their participation in the management of rainwater and the impact on the reduction of urban heat island effects. The research will allow identifying potential locations for the new low impact development forms in the city.

Student tasks

Developing a map in GIS based on available data showing the location of green roofs in Krakow; analysis of the location in the city and the number of facilities with green roofs in the immediate proximity and type of sewage system; conclusions