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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: Fall 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 2019) 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

Computational modeling of oxygen transfer from bubbles to liquid to improve the understanding of aeration process

Dublin City University

Master

Details

Supervisor: Thomas Abadie
Department: Mechanical and Manufacturing Engineering, DCU Water Institute
Keywords:  microbubbles, mass transfer, surface tension, numerical modeling, two-phase flow modeling.
Time frame/ Semester: From February 2018 (flexible)

Project background

The MSc thesis will follow a recent project involving the DCU Water Institute and ABP Food Group, which objective was to investigate oxygen transfer efficiency to improve aeration process and reduce operating costs of a wastewater treatment plant. 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) allows to enhance 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. A computational tool is also being used to study the diffusion of oxygen from microbubbles clouds to water. However, while microbubbles show promising results ([1] and our experiments), wastewater is a complex system due to the presence of micro-organisms and biochemical activity and a better understanding of the biochemical and physical mechanisms is required. 

Research focus

The MSc thesis will focus on the computational modeling of oxygen transfer from bubbles to liquid in order to improve the understanding of aeration process. The current model is based on a lagrangian approach from the open source computational platform OpenFOAM (MPPICFoam). Bubbles consist in spheres smaller than the mesh and the forces acting between the discrete and the continuous phase are introduced with existing models and correlations [2]. The advection-diffusion equation for the concentration of oxygen in the liquid is solved and coupled to the lagrangian bubbles through a source term based on transfer coefficients from the literature. However, the transfer mechanisms at the scale of a bubble in presence of surfactants is still not well understood and simulations (Volume Of Fluid or LevelSet) where the bubble is resolved will be performed. These first results will allow to correct usual correlations of transfer coefficients in presence of surfactants and implement those corrections for large scale lagrangian simulations. The simulations will be compared with experimental and literature data.

Student tasks

The student will be responsible for:

  • Validation of the implementation of variable surface tension on bubble dynamics with existing literature (Marangoni stress due to surfactants [3]).
  • Perform numerical simulations of oxygen transfer at the scale of a single bubble in presence of surfactants and compare with literature ([4,5]).
  • Implement and validate corrected transfer coefficients for aqueous solutions with surfactants (programming skills required).
  • (it time allows) Addition of chemical species in the liquid which react and consume oxygen to model wastewater (interaction with microbiologists).

Literature :

[1] K. Muroyama, K. Imai, Y. Oka, J. Hayashi, Mass transfer properties in a bubble column associated with micro-bubble dispersions, Chemical Engineering Science, 2013, 100:464-473.
[2] P.J. O’Rourke, D.M. Snider, An improved collision damping time for MP-PIC calculations of dense particle flows with applications to polydisperse sedimenting beds and colliding particle jets, Chemical Engineering Science, 2010, 65:6014-6028.
[3] S. Takagi, Y. Matsumoto, Surfactant Effects on Bubble Motion and Bubbly Flows, Annual Review of Fluid Mechanics, 2011, 43:615-636.
[4] R. Sardeing, P. Painmanakul, G. Hébrard, Effect of surfactants on liquid-side mass transfer coefficients in gas-liquid systems: a first step to modeling, Chemical Engineering Science, 2006, 61:6249-6260.
[5] M. Jimenez, N. Dietrich, J.R. Grace, G. Hébrard, Oxygen mass transfer and hydrodynamic behaviour in wastewater: Determination of local impact of  surfactants by visualization techniques, Water Research, 2014, 58:111-121.

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
Department: Mechanical and Manufacturing Engineering, DCU Water Institute
Keywords:  Fluid Structure Interaction, DIC, PIV, Experimental flow analysis
Time frame/ Semester: From February 2018 (flexible)

Description:

Project background

A large scale collaborative project involving the Dublin City University Water Institute and a EU consortium of universities and SMES will aim to study the anti-fouling and drag reduction characteristics of 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 is expected to start in April 2018 and the proposed Masters’ thesis is intended to prepare the experimental part by completing both design and built of a tunnel and drag measurement cell and high accuracy pressure measurements while allowing Laser based flow characterisation.

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. The project will involve a review of the literature to determine the preferred and optimal approach and then design and build of the experimental tunnel.  In parallel, micro-textured surfaces will be designed and manufactured to allow testing and validation of the tunnel and experimental system by comparison against published results.

Student tasks

The student will be responsible for:

  • Review of the literature to identify alternative experimental systems for the characterisation of micro-textured surface in turbulent flow.
  • Characterisation of the tunnel and flow over the micro-textures using either or both the experimental system built and computational flow modelling.

Experimental characterisation of flexible membrane dynamics due to Fluid Structure Interaction

Dublin City University

Master

Details

Supervisor:  Dr Yan Delauré
Department: Mechanical and Manufacturing Engineering, DCU Water Institute
Keywords:  Fluid Structure Interaction, DIC, PIV, Experimental flow analysis
Time frame/ Semester: From February 2018 (flexible)

Description:

Project background

A collaborative project involving the Dublin City University Water Institute and Sulzer Pump Solutions Ireland will start in January 2018. The project will involve both experimental and computational research and aims to characterise the transport of flexible structures 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. It was designed to extend research that has been ongoing for the past 4 years and improve an existing experimental water tunnel on the one hand and a Fluid Structure Interaction simulation solver on the other hand.

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 (https://www.dantecdynamics.com/digital-image-correlation) and 2D planar Particle Image Velocimetry (https://www.dantecdynamics.com/particle-image-velocimetry). A new support frame to simplify the DIC calibration has been built and a new stereoscopic PIV system has been integrated by a past student from TU Berlin. Both will be available for this Master project which will aim to perform experiments to characterise the dynamics of fluid structure interaction for a range of membranes and flow conditions. This will require that the student reviews the theoretical foundations of PIV as a measurement technique and characterise the measurement accuracy with the DCU setup for a set of benchmark test cases. Once this is completed the student will be able to study a range of structures and their response to fluid flow under varying conditions. Both Linear and Non-linear materials and deformation will be considered. The experimental work will be used to provide validation test cases for the computational models.

Student tasks

The student will be responsible for:

  • Validation of experimental measurement from published benchmark cases.
  • Experimental characterisation of flexible membrane FSI under range of conditions. Note that very little published research exists on this topic.

Advanced Oxidation Processes (AOP) for Landfill Leachate Treatment

Norwegian University of Technology Trondheim

Master

Details

Supervisor: Meyn, Thomas and Ambauen, Noemi
Department: Hydraulic and Environmental Engineering
Keywords: advanced oxidation processes, persistent organic pollutants, treatment, cold climate conditions
Time frame/ Semester: From March 2017 (flexible)

Description:

Project background

The discharge of landfill leachate to a water body is becoming more stringent in Norway by 2020 due to EU-legislation, making advanced effluent treatment necessary. Advanced oxidation processes (AOP) are investigated as a viable element, considering the landfill leachate characteristics as well as the given geographical and local conditions. A low BOD5/COD ratio, low average temperatures and limited space favour the application of an AOP instead of a biological treatment.

Research focus

Both, electrochemical oxidation (Figure 1) and ozonation are investigated in this project, focusing on oxidation of persistent organic pollutants. Degradation kinetics and pathways will be studied under cold climate conditions, in dependence on different treatment conditions. Another focus is the monitoring of hydroxyl- and other radicals during the oxidation process. Advanced analytical tools will be applied in the project, such as HPLC, GC/MS and Electron paramagnetic resonance (EPR).

Student tasks

Students will be given an independent subtask within the project, there they are responsible for carrying out bench and lab-scale experiments, as well as relevant sample preparation and analysis.

Organic matter utilization from rainwater collection system sludges

Cracow University of Technology

Master

Details

Supervisor: Rybicki SM, DSc,
Department: Environmental Engineering
Keywords: Sludge minimization, rainwater systems, circular solutions,
Time frame/ Semester: Spring 2018 (March-June 2018)

Description:

MSc thesis will focus on organic matter content in sludge from rainwater collection systems. These may carry contaminants from roads, yards, uncontrolled inflows which create significant problems with its handling, so usually it leads to receiving water contamination. The scope of the work is to perform laboratory tests on sludge collected at various discharge points, conducting its quality tests and propose solutions to solve problems. Option 1 will be respirometric tests to check whether this organics can be converted int a biogas (mixed with conventional sludges). Option 2 will be tests on chemical constituency of ashes from its combustion with respect to application as construction materials.

2D numerical modelling of seepage field and stability of the levee cross-section including different engineering renovation solutions

Cracow University of Technology

Master

Details

Supervisor: PhD eng. Krzysztof Radzicki
Department: Faculty of Environmental Engineering,
Institute of Water Engineering and Water Management
Keywords: numerical modelling, stability, seepage, levee, safety
Time frame/ Semester: Spring 2017 (March-June 2017) or Autumn 2017

Description:

This project contains 2D numerical modelling of seepage field and stability of the levee cross-section and takes into consideration some different engineering solutions (impermeable barriers, drainage system) of this levee renovation as well modeling of actual (not modernized) levee state.
Modelling should be carried out in numerical modelling Zsoil software. Cracow University of Technology have professional license of this software as well students licenses to work out of our internal university network.

Analysis of the influence of the spatial planning in the catchment, amount of the rainfall and the degree of sealing on the runoff using the geomorphological model raifall-runoff

Cracow University of Technology

Details

Supervisor: Elżbieta JAROSIŃSKA, PhD.
Department: Faculty of Environmental Engineering,
Keywords: urbanised catchment, rainfall hyetographs, rainfall-runoff model, land surface sealing, urban runoff
Time frame/ Semester: Spring 2017 (March-June 2017) or Autumn 2017

Description:

Urbanisation and climate change have significant impact on disturbing water balance in catchments. Uncontrolled urban development, increased land surface sealing, and increasingly appearing heavy rainfall cause local inundations called urban flooding.
The purpose of the work is the estimation of impact of amount of the rainfall and the degree of sealing on the runoff in the catchment using the geomorphological model raifall-runoff.

Impact of traffic road on rainwater quality

Cracow University of Technology
Co operation MPWIK waterworks

Master

Details

Supervisor: Rybicki SM, DSc or Professor Cimochowicz M
Department: Faculty of Environmental Engineering,
Keywords: urainwater systems, heavy metals, water contamination
Time frame/ Semester: Summer 2018 (September 2018 – March 2019)

Description:
MSc thesis will focus on analysis of samples of rainwater from municipal system (separated type), addresses towards most typical contamination and its range. Special emphasis will be on heavy metals content . Optional will be analyses of oil-related products in such a rainwater instead of heavy metals. Selected oil-separating devices will be under student’s supervision to check real reliability of such facilities.