Ústav vodních staveb
Browse
Recent Submissions
Now showing 1 - 5 of 42
- ItemFree flow over a partially contracted thin-plate weir with a triangular notch ofangle 20.23° and zero weir height(Sciendo, 2025-06-01) Pospíšilík, Šimon; Kotaška, Stanislav; Duchan, David; Zachoval, Zbyněk; Orfánus, Martin; Šoltész, Andrej; Gruchot, Andrzej Tadeusz; Zydroń, TymoteuszThe paper explores flow characteristics in the case of free flow of clean water over a partially contracted thin-plate weir with a triangular notch of angle 20.23° and with zero weir height above the bottom of the approach channel ofrectangular cross-section at 5 approach channel widths and 7 heads. The description was based on the results from experimental research and numerical simulations. The numerical simulations allowed the description of the characteristics in parts of the flow where measurements were difficult to perform. The experimental research quantifies the validity of the numerical simulations and establish recommendations for construction of numerical models. The boundary between a partially contracted weir and a fully contracted weir was established by dimensionless approach channel width of the value 0.32, the flow characteristics (water surface, velocity) in the full range of the partially contracted weir (dimensionless approach channel width in range 0.32 BU* 1.00), and recommendations for the placement of a cross-section to measure water surface level for determine the heads (dimensionless distance 4 x* 2) were verified.
- ItemDesign of Web GIS Application for Planning of Military River Crossing(Univerzita obrany Brno, 2024-11-07) Dohnal, Filip; Straka, Šimon; Duchan, DavidSuccessful ground military operations necessitate thorough comprehension of the operational environment, particularly terrain and water features. This article advocates for the utilization of Geographic Information System (GIS) technology to develop a dynamic web application aimed at analyzing and planning watercourse crossings. By harnessing the capabilities of ArcGIS Pro and ArcGIS Online, the proposed application integrates hydrological and terrain data to provide comprehensive insights into the feasibility of crossing specific water obstacles under varying conditions. Key considerations include terrain characteristics, river channel profiles, and the tactical specifications of military vehicles. While the application is currently in the conceptual phase and awaits verification, its potential in enhancing operational planning for the Czech Armed Forces is underscored. This GIS-based approach promises to enhance decision-making processes by offering real-time, interactive support for evaluating and strategizing water obstacle crossings within military operations.
- ItemThe application of a minimum specific energy concept for a fish ladder design(Polish Academy of Sciences, 2022-05-13) Kubrak, Michal; Smolinski, Blažej; Říha, Jaromír; Kodura, Apoloniusz; Popielski, Pawel; Jablonski, KamilStructural solutions in terms of fish ladders and the use of natural materials to construct them often raise concerns regarding the possibility of using the standard calculation methods. The fish ladder being designed on the Wisłok river consists of three pools, separated from each other by baffles made of rock boulders. The purpose of this study was to analyze water surface profiles for fish ladder at specific values of flow rates. The paper presents the results of hydraulic calculations under the conditions of constant flow rate based on the concept of a minimum specific energy. According to this method, water flow through boulders is critical. Thus, it does not take into account head losses, which are hard to estimate and which are the integral part of typical calculation methods, e.g. the use of equations to determine the flow rate of a weir. An additional advantage of this method is that there is no need to assume the flow pattern of one specific weir. Verification calculations of the water depths were conducted using the HEC–RAS software, under an assumption of an one-dimensional steady water flow. Water depths in the fish ladder, calculated using both methods, were similar, despite the adopted different calculation concepts, and can be used in ichthyologic analyses.
- ItemAnalysis of Seepage in a Laboratory Scaled Model using Passive Optical Fiber Distributed Temperature Sensor(MDPI, 2020-01-29) Ghafoori, Yaser; Maček, Matej; Vidmar, Andrej; Říha, Jaromír; Kryžanowski, AndrejAbstract: Seepage is the key factor in the safety of dikes and earthfill dams. It is crucial to identify and localize the seepage excesses at the early stages before it initiates the internal erosion process in the structure. A proper seepage monitoring system should ensure a continuous and wide area seepage measurement. Here, continuous monitoring of seepage at the laboratoryscale is achieved by a passive optical fiber Distributed Temperature Sensing (DTS) system. An experimental model was designed which consists of initially unsaturated sand model, water supply, seepage outflow, optical fiber DTS system, and water and air temperature measurement. Initially, the sand temperature was higher than the temperature of the seepage water. An optical fiber DTS system was employed with a hightemperature resolution, short sampling intervals and short time intervals for temperature monitoring in the sand model. In the system, the small variation in the temperature due to groundwater flow was detected. The numerical analysis was conducted for both the seepage process and the heat transfer progression in the sand model. The results of the heat flow simulation were evaluated and compared with the measured temperature by the optical fiber DTS. Obvious temperature reduction was obtained due to seepage propagation in the sand. The rate of temperature reduction was observed to be dependent on the seepage flow velocity.
- ItemUnsteady Flow and River Bed Stratification Mutual Impact on Scour at the Abutments(University of Split, 2020-04-08) Gjunsburgs, Boriss; Pařílková, JanaThe floods of different probability, sequence, frequency, duration, and the riverbed with different grain sizes, numbers, sequences, and thickness of the layers are one of the reasons for the bridge`s abutments failure because of scour. Although the problem is very topical, the mutual impact of multiple floods and stratified riverbed conditions on scour at the bridge abutments has not been studied. The method for computing scour development in time at bridge abutments was elaborated and confirmed by tests results. The method enables the computer to perform modelling of the mutual impact of unsteady flow and bed layering of scour processes. Computer modelling was made to expand scenarios for tests data in flume for unsteady flow for two steps of hydrograph with different dischargers and for the bed layers with varying grain sizes, numbers, sequence, and thickness. This approach makes it possible to estimate in advance mutual impact, with different scenarios, floods and geological data on the depth of scour at vertical wall abutment, at the design stage or during the maintenance period of the bridge crossing.