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Wake flow field of a wall-mounted pipe with spoiler on a rough channel bed

Devi Kalpana, Mishra Shivam, Hanmaiahgari Prashanth Reddy, Pu Jaan H.

Acta Geophysica

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2023

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Vol. 71, no. 6

2865--2881

EN

This research work focuses on the wake flow region of a cylinder with a spoiler on a rough bed under steady flow conditions. The acoustic Doppler velocimetry was used for the measurement of three-dimensional velocity data for two Reynolds numbers in a fully developed turbulent flow around the cylinder with a spoiler. The mean flow velocities, second-order turbulence structures, and conditional statistics were investigated in the wake region of the spoilered cylinder. The flow was separated from the spoiler with the formation of two shear layers between free surface flow and recirculating flow. It is observed that the flow is reattaching to the bed at 11D irrespective of the Reynolds number. Downstream of the cylinder, the mean velocity distributions are asymmetric due to the wall-wake effect, and the point of inflection is observed for each velocity profile at z = 0.40ẟ. The turbulence intensities, Reynolds stresses, and TKE are highly enhanced in the wake region of the cylinder as compared to their respective upstream values for both runs. The turbulence intensities, Reynolds normal stresses, Reynolds shear stresses, and turbulent kinetic energy are attaining peaks at z = 0.4ẟ for all the streamwise locations, and the peaks are found to be highest at x = 10D. The quadrant analysis results indicate that the sweeps are dominating bursting events in the inner and intermediate layers, while ejections are dominating in the outer layer of the wake region. As the hole size, H increases ejections stress fraction rises as compared to that of the sweeps in the wake region for z = 0.2-0.7 h.

2

An Integrated Approach of Profi le Studies for Surface Water Velocity on a Steep Slope in a Rectangular Channel

Ayalew Abebe Temesgen, Koshuma Abera Ermias, Ayele Mesfi n Amaru, Dirate Democracy Dilla

Advances in Science and Technology. Research Journal

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2022

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Vol. 16, no 2

74--80

EN

The flow velocity of water and its accurate surface profile estimation is important parameter as changes in climate increases the uneven rainfall patterns causing flood in downstream. It is important to know the velocity profile in steep open channel flows for solving the soil erosion, flooding and sediment transport problems in rivers or streams on steep slopes. A fixed bed laboratory experiment for a rectangular channel with steep slope is conducted to find the velocity profiles and surface profiles at different sections. Velocity profiles are presented at different sections in rectangular channel with steep slope. The outcome of the laboratory based experimental investigation shows that the velocity and surface profiles are influenced by the depth of flow of water and channel bed slope respectively.

3

Współczesne metody instrumentalnego pomiaru prędkości przepływu wody w korytach otwartych

Wójcik K., Wdowikowski M.

Technologia Wody

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2015

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Nr 1 (39)

32--39

PL

Istotą wykonywania pomiarów hydrometrycznych w korytach rzecznych jest wyznaczenie wartości prędkości oraz strumienia objętości przepływu wody dla danego napełnienia. Współcześnie coraz szersze zastosowanie znajdują urządzenia akustyczne wykorzystujące efekt Dopplera. W korytach rzecznych i jeziorach już od lat 90. największe zainteresowanie skupiają akustyczne przepływomierze profilujące ADCP (Acoustic Doppler Current Profilers). W niniejszej pracy zostały przedstawione podstawy teoretyczne pomiarów hydrometrycznych oraz przykładowe wyniki badań IMGW-PIB Oddział we Wrocławiu, który w ramach państwowej służby hydrologiczno-meteorologicznej zobowiązany jest do prowadzenia przedmiotowych pomiarów. Z uwagi na różnorodny sprzęt pomiarowy jakim dysponuje IMGW-PIB zaprezentowano zestawienie klasycznego pomiaru młynkiem hydrometrycznym z współcześnie stosowanymi urządzeniami akustycznymi, dla różnego rodzaju cieków.

EN

The primary goal of hydrometrie measurements in river channels is to record the water velocity and water level (depth) at a specific flow rate. Nowadays, more frequent use of acoustic devices exploiting the Doppler effect is made both for land surface and oceanographic waters. From the 90s a significant progress has been made on acoustic flow profiling, termed ADCP (Acoustic Doppler Current Profiler), currently widely used in hydrometry. IMGW-PIB (Institute of Meteorology and Water Management - National Research Institute) is also implementing these instruments into the regular hydrometrie service. In the paper both the theoretical background of the ADCP and sample records are presented and discussed. Also a reference is made to the results obtained by classic propeller instruments for a variety of field conditions. Concluding, despite of some limitations in use and in tracking water velocity, the ADCP’s offer new possibilities and deliver new (quantity and quality) value to the hydrometry and hydrology.