Abstract. The current research work presents experiments of an essentially incompressible fluid flow in pipes. The experimental equipment consists of a horizontal pipe including a gate valve, a Venturi meter, a wide angle diffuser, an orifice plate, a 90-degree elbow and pressure tappings. An elbow connects the pipe to a rotameter with further pressure tappings. All pressure tappings connected to manometers held on a vertical panel behind the pipe work and show pressure at various points. The effect of the pipe geometry in the flow pattern is presented. Furthermore head losses are estimated, at specific stream-wise cross-sections, for mass flow rate numbered from 0.056 to 0.411 l/s. The manometers measure and clearly show pressure distribution against a calibrated scale. The diagrams of mass flow rate and head losses are presented in specific crosssections, where geometry changes. All measurements were calibrated and validated in a maximum standard deviation difference of 5%. The head losses decrease as the mass flow rate decreases, for all pipe geometries. In the future the experimental results can be used to verify numerical simulation results.
Floods are lethal and destructive natural hazards. The Mediterranean, including Greece, has recently experienced many flood events (e.g., Medicanes Zorbas and Ianos), while climate change results in more frequent and intense flood events. Accurate flood mapping in river areas is crucial for flood risk assessment, planning mitigation measures, protecting existing infrastructure, and sustainable planning. The accuracy of results is affected by all simplifying assumptions concerning the conceptual and numerical model implemented and the quality of geospatial data used (Digital Terrain Models—DTMs). The current research investigates flood modelling sensitivity against geospatial data accuracy using the following DTM resolutions in a mountainous river sub-basin of Thessaly’s Water District (Greece): (a) open 5 m and (b) 2 m data from Hellenic Cadastre (HC) and (c) 0.05 m data from an Unmanned Aerial Vehicle (UAV) topographical mission. RAS-Mapper and HEC-RAS are used for 1D (steady state) hydraulic simulation regarding a 1000-year return period. Results include flood maps and cross section-specific flow characteristics. They are analysed in a graphical flood map-based empirical fashion, whereas a statistical analysis based on the correlation matrix and a more sophisticated Machine Learning analysis based on the interpretation of nonlinear relationships between input–output variables support and particularise the conclusions in a quantifiable manner.
This paper reports on a laboratory study that was performed in an experimental model in the Technological Educational Institute of Thessaly. The current research work examines the water surface profile variation in abruptly altered open channel topography. The objective is to investigate the effects of river bottom sills on flow depth for river control protection against floods. A rectangular bottom sill with one edge rounded was placed on the bottom of a rectangular, horizontal, laboratory open flume and measurements were performed of free-surface flow depth over the bottom sill, under steady flow conditions, for different inflow discharges. Moreover, the HEC-RAS simulation model was used to numerically simulate the water surface variation over the rectangular bottom sill, under steady flow conditions. A mixed flow regime simulation was performed in order to validate the transition from subcritical to supercritical flow conditions. The computed flow depth variation over the rectangular bottom sill was compared with the obtained experimental measurements in order to demonstrate the accuracy of the performed measurements. The presented experimental data may be used to assist in the development of new and the verification and refinement of existing river hydraulic numerical simulation models, particularly those which use non-hydrostatic pressure distribution.
The Zambezi Basin, a semi-arid 1.4 Mio km 2 catchment area spreading across eight countries, constitutes a highly complex system. With several large dams, namely Kariba, Cahora Bassa, Kafue Gorge and Itezhi-Tezhi, the basin's hydrology is also influenced by vast wetlands with high ecological value such as the Barotse plains, the Mana Pools or the Kafue flats. The African DAms ProjecT (ADAPT) is an interdisciplinary research project aiming to develop an integrated set of methods that help assessing the ecological and socio-economic effects of dams. A comprehensive evaluation and characterization of the flow regimes before and after the dam's construction is a stepping stone towards this goal. The analysis is based on historical data, taking into account the evolution of existing reservoirs and hydropower plants. Three indicators are considered to describe the flow regimes in the basin. They allow quantifying the seasonal transfer of the water, the subweekly flow fluctuations and the intensity and frequency of the flow changes. In a further stage, a semi-distributed conceptual hydrological model will be built to simulate the flow regime with and without dams for actual and future hydrological scenarios.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.