Upgrade of the hydraulics laboratory for the modeling of water supply networks & design and operation optimization study
Duration: September 2012–August 2015
Budget: €34 422
Commissioned by: Research Promotion Foundation of Cyprys
Project director: D. Koutsoyiannis
Principal investigator: P. Papanicolaou
The main components of the project are: (a) Upgrading of the existing technological equipment of the Cyprus University of Technology, for supporting the research needs; (b) Development of a digital imprint of a selected water supply network (Paphos Municipality), with combined use of state-of-the-art technologies, such as GPS, GIS and SRS; (c) Development of a generalized modelling framework and related computational/mathematical tools (in terms of hydraulic simulation models and multiobjective evolutionary algorithms), which will be tested in the optimization of the design and operation of the pilot water supply network; (d) Development of an experimental representation aimed at improving the design and operation of the network and its systems, (e) Experimental verification of the computational results and development of know-how in matters relating to systems of supervision and self-regulation of pumps and valves. NTUA mainly contributes in water supply network modelling issues, focusing on the development of the optimization framework and their integration within a computational system. Moreover, NTUA provides support in the formulation of the specifications for the upgrading of the laboratory equipment and the implementation of the experiments.
Integrated study for the investigation of the quantity, quality and recovery of the underwater springs of the Stoupa region in Municipality of Lefktros, Messinia
Duration: January 2009–December 2010
Budget: €220 000
Project director: D. Koutsoyiannis
Principal investigator: P. Papanicolaou
The main objective of the project is to investigate the possibility of exploitation of the underwater springs of Stoupa, in the Municipality of Lefktra. The contribution of NTUA is the evaluation of the possible freshwater capture works from the underwater spring. The project comprises two stages: (a) the investigation of the problem and the development of a methodology for the capture, transport and temporary storage of the freshwater, which includes field work in a pilot study, and the construction and testing of the temporary pilot facility, and (b) the outline of the works required for the transport and storage of potable water.
Maintenance, upgrading and extension of the Decision Support System for the management of the Athens water resource system
Duration: October 2008–November 2011
Budget: €72 000
Project director: N. Mamassis
Principal investigator: D. Koutsoyiannis
This research project includes the maintenance, upgrading and extension of the Decision Support System that developed by NTUA for EYDAP in the framework of the research project “Updating of the supervision and management of the water resources’ system for the water supply of the Athens’ metropolitan area”. The project is consisted of the following parts: (a) Upgrading of the Data Base, (b)Upgrading and extension of hydrometeorological network, (c) upgrading of the hydrometeorological data process software, (d) upgrading and extension of the Hydronomeas software, (e) hydrological data analysis and (f) support to the preparation of the annual master plans
P. Dimitriadis, D. Koutsoyiannis, T. Iliopoulou, and P. Papanicolaou, A global-scale investigation of stochastic similarities in marginal distribution and dependence structure of key hydrological-cycle processes, Hydrology, 8 (2), 59, doi:10.3390/hydrology8020059, 2021.
To seek stochastic analogies in key processes related to the hydrological cycle, an extended collection of several billions of data values from hundred thousands of worldwide stations is used in this work. The examined processes are the near-surface hourly temperature, dew point, relative humidity, sea level pressure, and atmospheric wind speed, as well as the hourly/daily streamflow and precipitation. Through the use of robust stochastic metrics such as the K-moments and a secondorder climacogram (i.e., variance of the averaged process vs. scale), it is found that several stochastic similarities exist in both the marginal structure, in terms of the first four moments, and in the secondorder dependence structure. Stochastic similarities are also detected among the examined processes, forming a specific hierarchy among their marginal and dependence structures, similar to the one in the hydrological cycle. Finally, similarities are also traced to the isotropic and nearly Gaussian turbulence, as analyzed through extensive lab recordings of grid turbulence and of turbulent buoyant jet along the axis, which resembles the turbulent shear and buoyant regime that dominates and drives the hydrological-cycle processes in the boundary layer. The results are found to be consistent with other studies in literature such as solar radiation, ocean waves, and evaporation, and they can be also justified by the principle of maximum entropy. Therefore, they allow for the development of a universal stochastic view of the hydrological-cycle under the Hurst–Kolmogorov dynamics, with marginal structures extending from nearly Gaussian to Pareto-type tail behavior, and with dependence structures exhibiting roughness (fractal) behavior at small scales, long-term persistence at large scales, and a transient behavior at intermediate scales.
Full text: http://www.itia.ntua.gr/en/getfile/2114/1/documents/hydrology-08-00059-v5.pdf (7374 KB)
A. Koskinas, A. Tegos, P. Tsira, P. Dimitriadis, T. Iliopoulou, P. Papanicolaou, D. Koutsoyiannis, and Τ. Williamson, Insights into the Oroville Dam 2017 spillway incident, Geosciences, 9 (37), doi:10.3390/geosciences9010037, 2019.
In February 2017, a failure occurring in Oroville Dam’s main spillway risked causing severe damages downstream. A unique aspect of this incident was the fact that it happened during a flood scenario well within its design and operational procedures, prompting research into its causes and determining methods to prevent similar events from reoccurring. In this study, a hydroclimatic analysis of Oroville Dam’s catchment is conducted, along with a review of related design and operational manuals. The data available allows for the comparison of older flood-frequency analyses to new alternative methods proposed in this paper and relevant literature. Based on summary characteristics of the 2017 floods, possible causes of the incident are outlined, in order to understand which factors contributed more significantly. It turns out that the event was most likely the result of a structural problem in the dam’s main spillway and detrimental geological conditions, but analysis of surface level data also reveals operational issues that were not present during previous larger floods, promoting a discussion about flood control design methods, specifications, and dam inspection procedures, and how these can be improved to prevent a similar event from occurring in the future.
Full text: http://www.itia.ntua.gr/en/getfile/1926/1/documents/geosciences-09-00037-2.pdf (6834 KB)
M. Chalakatevaki, P. Stamou, S. Karali, V. Daniil, P. Dimitriadis, K. Tzouka, T. Iliopoulou, D. Koutsoyiannis, P. Papanicolaou, and N. Mamassis, Creating the electric energy mix in a non-connected island, Energy Procedia, 125, 425–434, doi:10.1016/j.egypro.2017.08.089, 2017.
As the electric energy in the non-connected islands is mainly produced by oil-fueled power plants, the unit cost is extremely high due to import cost. The integration of renewable resources in the energy mix is essential for reducing the financial and environmental cost. In this work, various energy resources (renewable and fossil fuels) are evaluated using technical, environmental and economic criteria with an emphasis to biomass, pumped hydro storage and replacement of oil power plants. Finally, a synthesis is presented as a toy-model in an Aegean island that satisfies the electric energy demand including base and peak electric loads.
Full text: http://www.itia.ntua.gr/en/getfile/1733/1/documents/electric_mix_energy_procedia.pdf (1118 KB)
Other works that reference this work (this list might be obsolete):
|1.||Bakanos, P. I., and K. L. Katsifarakis, Optimizing operation of a large-scale pumped storage hydropower system coordinated with wind farm by means of genetic algorithm, Global Nest Journal, 2019.|
|2.||Giudici, F., A. Castelletti, E. Garofalo, M. Giuliani, and H. R. Maier, Dynamic, multi-objective optimal design and operation of water-energy systems for small, off-grid islands, Applied Energy, 250, 605-616, doi:10.1016/j.apenergy.2019.05.084, 2019.|
P. Dimitriadis, D. Koutsoyiannis, and P. Papanicolaou, Stochastic similarities between the microscale of turbulence and hydrometeorological processes, Hydrological Sciences Journal, 61 (9), 1623–1640, doi:10.1080/02626667.2015.1085988, 2016.
Turbulence is considered to generate and drive most geophysical processes. The simplest case is the isotropic turbulence. In this paper, the most common three-dimensional power-spectrum-based models of isotropic turbulence are studied in terms of their stochastic properties. Such models often have a high-order of complexity, lack in stochastic interpretation and violate basic stochastic asymptotic properties, such as the theoretical limits of the Hurst coefficient, in case that Hurst-Kolmogorov behaviour is observed. A simpler and robust model (which incorporates self-similarity structures, e.g. fractal dimension and Hurst coefficient) is proposed using a climacogram-based stochastic framework and tested over high resolution observational data of laboratory scale as well as hydrometeorological observations of wind speed and precipitation intensities. Expressions of other stochastic tools like the autocovariance and power spectrum are also produced from the model and show agreement with data. Finally, uncertainty, discretization and bias related errors are estimated for each stochastic tool, showing lower errors for the climacogram-based ones and larger for power-spectrum ones.
V. Bellos, P. Kossieris, A. Efstratiadis, I. Papakonstantis, P. Papanicolaou, P. Dimas, and C. Makropoulos, Can we use hydraulic handbooks in blind trust? Two examples from a real-world complex hydraulic system, Proceedings of 7th IAHR Europe Congress "Innovative Water Management in a Changing Climate”, Athens, International Association for Hydro-Environment Engineering and Research (IAHR), 2022.
In this work, we investigate whether the parameters of physics-based hydraulic models, omnipresent in every relevant engineering handbook, can be used in blind trust in a real-world complex system. Here, we focus on the discharge coefficient for flows through a sluice gate and the Manning’s coefficient for steady flows, and we compare their typical literature values (experimentally derived) against the ones obtained via a “grey-box” calibration approach using real flow data from the complex raw-water conveyance system of Athens, Greece.
V. Bellos, P. Kossieris, A. Efstratiadis, I. Papakonstantis, P. Papanicolaou, P. Dimas, and C. Makropoulos, Fiware-enabled tool for real-time control of the raw-water conveyance system of Athens, Proceedings of the 39th IAHR World Congress, Granada, 2859–2865, doi:10.3850/IAHR-39WC2521716X20221468, International Association for Hydro-Environment Engineering and Research (IAHR), 2022.
The raw water network system of Athens (Greece) is a complex infrastructure comprising around 500 km of aqueducts, conveying water from four reservoirs to four water treatment plants, while serving several other local users. In this work, we focus on the most important part of this system, namely the open-channel aqueduct of Mornos. This extends over 200 km and has a dual operation, namely water conveyance and flow regulation through temporary storage along the channel. This is achieved by a series of Λ-type structures, each one comprising sluice gates for flow control and a lateral ogee spillway. Currently, the regulation across the channel is performed through empirical rules, and according to target volumes requested by the operators of the downstream water treatment plants, on a daily basis. However, this management policy, which is strongly based on expert’s knowledge, is neither sustainable nor safe, from a resilience perspective. Furthermore, the system is subject to occasional failures, due to undesirable overflows resulting to non-negligible water losses. In order to establish an optimal control policy, we developed an operational tool for the real- time scheduling of the sluice gate settings. Core of the tool is a conceptual model that incorporates the following assumptions: a) the operation of a Λ-type structure does not affect the operation of the other relevant structures; b) the Λ-type structure has two flow components, namely through the sluice gate and over the lateral spillway, which can be described by theoretical and semi-empirical hydraulic formulas, considering as unknown parameters the discharge coefficients of all sluice gates. On the other hand, the known model inputs are the geometrical characteristics of Λ-type structures and the real-time data for discharge, water level and gate opening, which are obtained from the telemetric monitoring system of the channel. In this respect, the key challenge is the determination of the discharge coefficients. This is employed through a grey-box approach, in which the model parameters are calibrated in continuous mode, using real-time data. To check the plausibility of the discharge coefficients, as derived by the real-time calibration phase, a comparison is made with the corresponding coefficients derived by historical data (off-line calibration). The tool, along with other analytics and algorithms developed, has been seamlessly integrated with the existing legacy system (e.g., SCADA, databases) of the system’s operator (Athens Water Supply and Sewerage Company - EYDAP), using the FIWARE standardization protocol.
Full text: http://www.itia.ntua.gr/en/getfile/2226/1/documents/04-07-014-1468.pdf (10700 KB)
P. Dimitriadis, A. Tegos, A. Petsiou, V. Pagana, I. Apostolopoulos, E. Vassilopoulos, M. Gini, A. D. Koussis, N. Mamassis, D. Koutsoyiannis, and P. Papanicolaou, Flood Directive implementation in Greece: Experiences and future improvements, 10th World Congress on Water Resources and Environment "Panta Rhei", Athens, European Water Resources Association, 2017.
The implementation of the European Directive 2007/60 is a crucial step towards the development of a sophisticated flood management plan for the main River Basin Districts by including any necessary structural measures. For this reason, extensive hydrological and hydraulic analysis is needed under the ubiquitous uncertainty which cannot be eliminated by numerical models. In this study, we present our experience from the directive implementation and we discuss structural components of uncertainty in the flood modelling practice mostly related to the river network. We propose and review some of the most efficient engineering practices by examining issues like: (a) the consistency and accuracy of the required input data of the topography such as the Digital Elevation Model, cross-sectional measurements of the river and maps of land use; (b) the uncertainty components related to the hydrological SCS-CN framework and other hydrological methods for the determination of the input hydrograph; (c) the theoretical framework of each hydraulic model such as the scheme dimension (1d, 2d or coupled 1d/2d), the type of solution of the numerical scheme (explicit or implicit), the boundary conditions and the type of discretization (grid or sectionbased); (d) the uncertainty components related to the flood inundation modelling, such as the roughness coefficient at the river and floodplain; (e) the necessity of validation data such as the flow discharge, the flood inundation area, and the velocity measurements.
A. N. Angelakis, D. Koutsoyiannis, and P. Papanicolaou, On the geometry of the Minoan water conduits, 3rd IWA Specialized Conference on Water & Wastewater Technologies in Ancient Civilizations, Istanbul, Turkey, 172–177, doi:10.13140/RG.2.1.4426.0083, International Water Association, 2012.
Several different types of conduits were found in archaeological excavations in Crete belonging to the Minoan period. They were used for water supply as well as for stormwater and wastewater removal and are made of stone or terracotta. The terracotta conduits were canals or pipes with rectangular or circular cross section. The most interesting conduits are the terracotta pipes of truncated conic shape which were never used before or later in other civilizations. An ongoing experiment using reconstructed pipes of this shape will be employed to evaluate their hydraulic behaviour and investigate possible advantages for certain flow conditions.
Full text: http://www.itia.ntua.gr/en/getfile/1203/1/documents/2012WWTAC_MinoanPipes.pdf (448 KB)
Other works that reference this work (this list might be obsolete):
|1.||#Angelakis, A. N., A. G. Lyrintzis and S. V. Spyridakis, Urban water and wastewater technologies in Minoan Crete, Greece, Proceedings 3rd IWA Specialized Conference on Water & Wastewater Technologies in Ancient Civilizations, Istanbul, Turkey, 208-214, 2012.|
|2.||#Angelakis, A. N., Water supply and sewerage in Minoan Crete: lessons and legacies, Proceedings of the 2nd Joint Conference of EYE-EEDYP "Integrated Water Resources Management for Sustainable Development" (Ed.: P. Giannopoulos and A. Dimas), 509-518, Patras, Greece, 2012.|
|3.||#Angelakis , A. N., G. De Feo , P. Laureano and A. Zourou, Minoan and Etruscan water and wastewater technologies: approaches and lessons learned, e-Proceedings of IWA Congress & Exhibition, Bussan, Korea, September 16-21, 2012.|
|4.||Angelakis , A. N., G. De Feo , P. Laureano and A. Zourou, Minoan and Etruscan hydro-technologies, Water, 5, 972-987, 10.3390/w5030972, 2013.|
|5.||Angelakis, A.N., and S.V. Spyridakis, Major urban water and wastewater systems in Minoan Crete, Greece, Water Science and Technology: Water Supply, 13 (3), 564-573, 2013.|
|6.||De Feo, G., G. Antoniou, H. F. Fardin, F. El-Gohary X. Y. Zheng, I. Reklaityte, D.Butler, S. Yannopoulos and A. N. Angelakis, The historical development of sewers worldwide, Sustainability, 6 (6), 3936-3974, 2014.|
|7.||#Angelakis, A. N., E. Kavoulaki and E. G. Dialynas, Sanitation and wastewater technologies in Minoan Era, Evolution of Sanitation and Wastewater Technologies through the Centuries, ed. by A.N. Angelakis and J.B. Rose, IWA Publishing, London, 2014.|
|8.||#El-Gohary, F.A., Evolution of sanitation and wastewater technologies in Egypt through centuries, Evolution of Sanitation and Wastewater Technologies through the Centuries, ed. by A.N. Angelakis and J.B. Rose, 55-68, IWA Publishing, London, 2014.|
|9.||#Mitchell, P.D., Sanitation, Latrines and Intestinal Parasites in Past Populations, Ashgate Publishing, 1-278, 2015.|
|10.||Juuti, P.S., G.P. Antoniou, W. Dragoni, F. El-Gohary, G. De Feo, T.S. Katko, R.P. Rajala, X.Y. Zheng, R. Drusiani and A.N. Angelakis, Short global history of fountains, Water, 7 (5), 2314-2348, 10.3390/w7052314, 2015.|
C. Farmakis, P. Dimitriadis, V. Bellos, P. Papanicolaou, and D. Koutsoyiannis, Investigation of the uncertainty of spatial flood inundation among widely used 1D/2D hydrodynamic models, European Geosciences Union General Assembly 2019, Geophysical Research Abstracts, Vol. 21, Vienna, EGU2019-15629, European Geosciences Union, 2019.
On several occasions, hydrodynamic models are applied in order to establish flood risk and flood hazard maps and evaluate the impacts of floods. More often these models are treated as deterministic tools and, as a result,the uncertainties stemmed from the modelling simplifications and assumptions are ignored. Specifically, when the spatial propagation of a flood wave is of interest the highest uncertainties emerge at the boundary conditions, at the model input parameters and even at the model structure. The aim of this research is to examine the aforementioned sources of uncertainty in benchmark scenarios. Three models are tested (i.e. the one-dimensional HEC-RAS, the quasi-two-dimensional LISFLOOD-FP, and a two-dimensional scheme of the OpenFOAM) on steady hydraulic conditions and uniform channel geometry. In each model a sensitivity analysis is performed by varying the grid resolution, the input discharge, the roughness coefficient in the channel and floodplain, and the channel longitudinal and lateral gradient. After statistically analyzing the fluctuation of the output parameters (i.e. the mean water velocity at the inflow and outflow cross section, and the water volume), the uncertainty in the different model configurations is quantified and compared.
Full text: http://www.itia.ntua.gr/en/getfile/1994/1/documents/Chrysanthos_Farmakis_poster1.pdf (2072 KB)
E. Chardavellas, P. Dimitriadis, I. Papakonstantis, D. Koutsoyiannis, and P. Papanicolaou, Stochastic similarities between the microscale of vertical thermal jet and macroscale hydrometeorological processes, European Geosciences Union General Assembly 2018, Geophysical Research Abstracts, Vol. 20, Vienna, EGU2018-17803-1, European Geosciences Union, 2018.
Most hydrometeorological processes (such as temperature, wind etc.) are governed by turbulent state. In this study, we seek for stochastic similarities between the correlation structure of hydrometeorological processes (as has been already derived from global analyses of surface stations) and experimental vertical thermal jet at different states. It is well established experimentally that a jet flow close to the nozzle (at the zone of the core) is laminar and far from the nozzle (at the zone of established flow) fully turbulent. We apply several stochastic tools (autocorrelation, power spectrum, climacogram etc.) at the two aforementioned zones as well as at the intermediate zone of flow establishment (5 to 15 diameters away from the nozzle) in an attempt to identify any stochastic similarities and differences between the three zones, and thus, between the laminar and turbulent flow state transition. For this, spatio-temporal temperature records are obtained on the plane of symmetry of heated vertical round jets (for a laboratory turbulent scale at the order of mm) using tracer concentration measurements via a planar laser induced fluorescence technique (PLIF). Finally, a characterization of jet thermal turbulent state is proposed based on the Hurst parameter that is used for the identification of the long-term persistent behavior (or else called Hurst-Kolmogorov behaviour) of a process.
Full text: http://www.itia.ntua.gr/en/getfile/1822/1/documents/EGU2018-17803-1.pdf (32 KB)
P. Dimitriadis, T. Iliopoulou, A. Efstratiadis, P. Papanicolaou, and D. Koutsoyiannis, Stochastic investigation of the uncertainty in common rating-curve relationships, European Geosciences Union General Assembly 2018, Geophysical Research Abstracts, Vol. 20, Vienna, EGU2018-18947-2, European Geosciences Union, 2018.
A common issue in the river analysis is that most discharges measurements are taken from stage measurements and then an empirical expression is applied often called rating curves. There are several empirical relationships to determine the rating curves in order to estimate the river discharge when the water-surface is known and vice versa. Here, we investigate the stochastic uncertainty induced in empirical expressions of common rating curves. For this, we perform exhaustive Monte-Carlo experiments by assuming a theoretical stochastic structure (with or without fixed trends) for the river stage and we estimate the change in the dependence structure and marginal distribution of the river discharge. We further perform a sensitivity analysis on the input parameters of the common stage-discharge expressions in order to identify and estimate the overall induced uncertainty. Finally, we discuss on the results and we derive some preliminary conclusions on whether a stochastic structure (including trends) empirically estimated in terms of stage can be arbitrarily translated into discharge.
Full text: http://www.itia.ntua.gr/en/getfile/1787/1/documents/EGU2018-18947-2.pdf (31 KB)
V. Daniil, G. Pouliasis, E. Zacharopoulou, E. Demetriou, G. Manou, M. Chalakatevaki, I. Parara, C. Georganta, P. Stamou, S. Karali, E. Hadjimitsis, G. Koudouris, E. Moschos, D. Roussis, K. Papoulakos, A. Koskinas, G. Pollakis, N. Gournari, K. Sakellari, Y. Moustakis, N. Mamassis, A. Efstratiadis, H. Tyralis, P. Dimitriadis, T. Iliopoulou, G. Karakatsanis, K. Tzouka, I. Deligiannis, V. Tsoukala, P. Papanicolaou, and D. Koutsoyiannis, The uncertainty of atmospheric processes in planning a hybrid renewable energy system for a non-connected island, European Geosciences Union General Assembly 2017, Geophysical Research Abstracts, Vol. 19, Vienna, EGU2017-16781-4, doi:10.13140/RG.2.2.29610.62406, European Geosciences Union, 2017.
Non-connected islands to the electric gird are often depending on oil-fueled power plants with high unit cost. A hybrid energy system with renewable resources such as wind and solar plants could reduce this cost and also offer more environmental friendly solutions. However, atmospheric processes are characterized by high uncertainty that does not permit harvesting and utilizing full of their potential. Therefore, a more sophisticated framework that somehow incorporates this uncertainty could improve the performance of the system. In this context, we describe several stochastic and financial aspects of this framework. Particularly, we investigate the cross-correlation between several atmospheric processes and the energy demand, the possibility of mixing renewable resources with the conventional ones and in what degree of reliability, and critical financial subsystems such as weather derivatives. A pilot application of the above framework is also presented for a remote island in the Aegean Sea.
Full text: http://www.itia.ntua.gr/en/getfile/1689/1/documents/EGU2017oral_16781_final.pdf (3038 KB)
P. Stamou, S. Karali, M. Chalakatevaki, V. Daniil, K. Tzouka, P. Dimitriadis, T. Iliopoulou, P. Papanicolaou, D. Koutsoyiannis, and N. Mamassis, Creating the electric energy mix of a non-connected Aegean island, European Geosciences Union General Assembly 2017, Geophysical Research Abstracts, Vol. 19, Vienna, EGU2017-10130-10, doi:10.13140/RG.2.2.36537.77927, European Geosciences Union, 2017.
As the electric energy in the non-connected islands is mainly produced by oil-fueled power plants, the unit cost is extremely high. Here the various energy sources are examined in order to create the appropriate electric energy mix for a non-connected Aegean island. All energy sources (renewable and fossil fuels) are examined and each one is evaluated using technical, environmental and economic criteria. Finally the most appropriate energy sources are simulated considering the corresponding energy works. Special emphasis is given to the use of biomass and the possibility of replacing (even partially) the existing oil-fueled power plant. Finally, a synthesis of various energy sources is presented that satisfies the electric energy demand taking into account the base and peak electric loads of the island.
Full text: http://www.itia.ntua.gr/en/getfile/1688/2/documents/posterEGU.pdf (2687 KB)
P. Dimitriadis, D. Koutsoyiannis, and P. Papanicolaou, Climacogram-based modelling of isotropic turbulence, Facets of Uncertainty: 5th EGU Leonardo Conference – Hydrofractals 2013 – STAHY 2013, Kos Island, Greece, European Geosciences Union, International Association of Hydrological Sciences, International Union of Geodesy and Geophysics, 2013.
The stochastic structure of isotropic and homogeneous turbulence is studied in terms of its climacogram. A stochastic model is presented and tested over observational data of different scales and isotropy ratios. Observational data include solar wind, atmospheric wind velocities, laboratory scale wind velocities and turbulent buoyant jet concentrations. Theoretical expressions of the spectrum, structural and autocorrelation functions produced directly from the model show good agreement with data and differences from the existing models of turbulence.
P. Dimitriadis, M. Liveri-Dalaveri, A. Kaldis, C. Kotsalos, G. Papacharalampous, and P. Papanicolaou, Zone of flow establishment in turbulent jets, European Geosciences Union General Assembly 2012, Geophysical Research Abstracts, Vol. 14, Vienna, EGU2012-12716, European Geosciences Union, 2012.
It is well established experimentally that as the Reynolds number increases the core of the jet diminishes and has smaller effects on the jet’s mean profiles (e.g. concentration, temperature, velocity). The scope of this project is to examine this relationship based on dimensional analysis and experimental data. For that, spatio-temporal temperature records are obtained on the plane of symmetry of heated vertical round jets (for a laboratory turbulent scale at the order of mm) using tracer concentration measurements via a planar laser induced fluorescence technique (PLIF). The investigation area is set close to the nozzle of the jets (5-6 diameters away), at the zone of flow establishment (ZFE), so as to determine the geometric characteristics (dimensions and shape) of the core as a function of the initial velocity and nozzle diameter. The ZFE is estimated through the absence of turbulent intensity fluctuations (assuming a 1% of the maximum intensity as a threshold value).
P. Dimitriadis, and P. Papanicolaou, Statistical analysis of turbulent positively buoyant jets, European Geosciences Union General Assembly 2012, Geophysical Research Abstracts, Vol. 14, Vienna, EGU2012-12672, European Geosciences Union, 2012.
The future aim of this work is to create a statistical model for turbulent positively buoyant jets. For this, a statistical analysis is presented here, for a two-dimensional (2D) spatio-temporal temperature records obtained from tracer concentration measurements on the plane of symmetry of vertical heated jet. Some of the statistical tools used in this analysis are the probability and probability density distributions, energy spectrum, climacogram and Hurst coefficient distribution, autocorrelation and structural functions. Moreover, the above measurements are compared with existing ones from the literature.
P. Dimitriadis, P. Papanicolaou, and D. Koutsoyiannis, Hurst-Kolmogorov dynamics applied to temperature ﬁelds for small turbulence scales, European Geosciences Union General Assembly 2011, Geophysical Research Abstracts, Vol. 13, Vienna, EGU2011-772, doi:10.13140/RG.2.2.22137.26724, European Geosciences Union, 2011.
Two-dimensional (2D) spatio-temporal temperature records obtained from tracer concentration measurements on the plane of symmetry of heated jets (small turbulence scale) are statistically analyzed and the presence of Hurst-Kolmogorov (HK) dynamics is detected. The 2D HK process is then ﬁtted to the data and synthetic time-varying and/or spatial ﬁelds are generated for temperature, which are consistent with the observed. Moreover, the 2D HK process is formulated assuming anisotropy, so as to take into account possibly different autocorrelation decay rates (Hurst coefﬁcients) in each dimension of the ﬁeld. In addition, the results are also investigated in comparison with Kolmogorov’s power spectrum model K41.
Other works that reference this work (this list might be obsolete):
|1.||#Deskos, G. B., P. G. Dimitriadis and P. N. Papanicolaou, Density stratification in the mixed regime of a buoyant jet in confined ambient, Proceedings of the 2nd Joint Conference of EYE-EEDYP "Integrated Water Resources Management for Sustainable Development" (Ed.: P. Giannopoulos and A. Dimas), 200-211, Patras, Greece, 2012.|
A. Efstratiadis, and P. Papanicolaou, Lecture notes on Hydraulic Structures and Dams, 93 pages, Department of Water Resources and Environmental Engineering – National Technical University of Athens, 2018.
P. Papanicolaou, Elements of steady flow in pressured pipes and open channels, 271 pages, Department of Water Resources and Environmental Engineering – National Technical University of Athens, 2014.
Full text: http://www.itia.ntua.gr/en/getfile/2145/1/documents/Applied_Hydraulics_2014.pdf (12325 KB)
A. Efstratiadis, I. Papakonstantis, P. Papanicolaou, N. Mamassis, D. Nikolopoulos, I. Tsoukalas, and P. Kossieris, First year synopsis, Modernization of the management of the water supply system of Athens - Update, Contractor: Department of Water Resources and Environmental Engineering – National Technical University of Athens, 55 pages, December 2020.
I. Papakonstantis, P. Papanicolaou, V. Kotsioni, M. Hondros, C. Memos, and D. Koutsoyiannis, Final report, Integrated study for the investigation of the quantity, quality and recovery of the underwater springs of the Stoupa region in Municipality of Lefktros, Messinia, Contractors: Hellenic Centre for Marine Research, Agricultural University of Athens, National Technical University of Athens, Department of Water Resources and Environmental Engineering – National Technical University of Athens, Athens, 2010.
Full text: http://www.itia.ntua.gr/en/getfile/1314/1/documents/EMP_Teyxos1.pdf (4224 KB)
Other works that reference this work (this list might be obsolete):
|1.||#Papakonstantis, I. G., P. N. Papanicolaou and E. G. Kastrinakis, Capture of fresh water from submarine springs: case study in Stoupa of Messinia, Proceedings of the 2nd Joint Conference of EYE-EEDYP "Integrated Water Resources Management for Sustainable Development" (Ed.: P. Giannopoulos and A. Dimas), 682-693, Patras, Greece, 2012.|
J. Papageorgiou, and P. Papanicolaou, Four day workshop HNMS 30.3.93 to 2.4.93, Hydroscope: Creation of a National Databank for Hydrological and Meteorological Information, Contractor: Department of Water Resources, Hydraulic and Maritime Engineering – National Technical University of Athens, Report 0/5, 425 pages, National Technical University of Athens, Athens, April 1993.
N. Mamassis, and P. Papanicolaou, Selection and calculation of secondary parameters in surface hydrology (More specifically STAGE-DISCHARGE and DISCHARGE-SEDIMENT LOAD relationships), Hydroscope: Creation of a National Databank for Hydrological and Meteorological Information, Report 1/4, 37 pages, Department of Water Resources, Hydraulic and Maritime Engineering – National Technical University of Athens, Athens, July 1993.
Full text: http://www.itia.ntua.gr/en/getfile/302/1/documents/er1_1-4.pdf (3629 KB)
P. Papanicolaou, and D. Koutsoyiannis, Guidelines for the layout of deliverable reports, Hydroscope: Creation of a National Databank for Hydrological and Meteorological Information, Report 0/1, 16 pages, Department of Water Resources, Hydraulic and Maritime Engineering – National Technical University of Athens, Athens, July 1992.
Full text: http://www.itia.ntua.gr/en/getfile/266/1/documents/er1_0-1.pdf (1511 KB)
P. Papanicolaou, D. Koutsoyiannis, and A. Stamou, Guidelines for the presentation of academic works in the Department of Water Resources & Environmental Engineering, Department of Water Resources and Environmental Engineering – National Technical University of Athens, Athens, 2012.
Full text: http://www.itia.ntua.gr/en/getfile/1323/1/documents/DWREE_InstructionsForReports.pdf (1843 KB)