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- ItemFlow over thin-plate weirs with a triangular notch – influence of the relative width of approach channel with a rectangular cross-section(Institute of Hydrology of the Slovak Academy of Sciences, 2024-06-01) Pospíšilík, Šimon; Zachoval, Zbyněk; Gabriel, PavelThe article deals with the determination of the influence of the relative width of an approach channel with a rectangular cross-section on the discharge of clean water flowing over thin-plated weirs with a triangular notch and zero height of the weir above the bottom of the approach channel. To evaluate the influence, the Kindsvater-Shen equation was modified by introducing the basic effective discharge coefficient and the coefficient of the relative width of the approach channel. The coefficient of the relative width of the approach channel was determined based on the evaluation of data from three extensive experimental research investigations. It is valid for the entire possible range of relative widths of the approach channel and for the range of notch angles from 5.25° to 91.17°. The relative error of discharge determination is approximately up to ±2% over the entire range of discharges used in the conducted experimental research. The evaluation made it possible to determine the boundary distinguishing the partially contracted weirs from the fully contracted weirs in terms of impact on discharge.
- ItemFlow structure in front of the broad-crested weir(EDP Sciences, 2014-11-18) Zachoval, Zbyněk; Roušar, LadislavThe paper deals with research focused on description of flow structure in front of broad-crested weir. Based on experimental measurement, the flow structure in front of the weir (the recirculation zone of flow and tornado vortices) and flow structure on the weir crest has been described. The determined flow character has been simulated using numerical model and based on comparing results the suitable model of turbulence has been recommended.
- ItemFlow over broad-crested weir with inflow by approach shaft – numerical model.(Faculty of Civil Engineering, Czech Technical University in Prague, 2021-04-01) Major, Jakub; Orfánus, Martin; Zachoval, ZbyněkIn the case of flow over rectangular broad-crested weir, where the inflow is realized by approach shaft, occurs influence of water surface level by approach flow velocity. The paper describes numerical model of flow including weir, approach and outlet shaft. Simulations of flow were created by 2D and 3D model with using three methods of turbulent modelling. In paper is evaluated water surface level for each model setup and then is compared with measured values.
- ItemSubmergence coefficient of full-width sharp-edged broad-crested rectangular weirs(VEDA, SLOVAK ACAD SCIENCES, 2019-10-01) Zachoval, Zbyněk; Major, Jakub; Roušar, Ladislav; Rumann, Ján; Šulc, Jan; Jandora, JanFull-width sharp-edged broad-crested rectangular weirs in the range 0.1 < h/L <= 0.3 situated in rectangular channels are frequently used in submerged flow conditions. To determine the discharge for the submerged flow, submergence coefficient and modular limit shall be known. This article deals with their determination upon a theoretic derivation and experimental research. The equation for modular limit has been determined from energy balance with simplifications. To validate it, extensive experimental research was carried out. However, the derived equation is too complicated for practical use which is why it was approximated by a simple equation applicable for the limited range. The equation for submergence coefficient was derived by modifying Villemonte's application of the principle of super-position and its coefficients were determined using the data from experimental research of many authors. The new system of equations computes the discharge more accurately than other authors' equations, with the error of approximately +/- 10% in full range of the measured data.