Search results for "Open channel"
showing 10 items of 33 documents
Flow Resistance Law in Channels with Flexible Submerged Vegetation
2005
In this paper, experimental data collected in a straight flume having a bed covered by grasslike vegetation have been used to analyze flow resistance for flexible submerged elements. At first, the measurements are used to test the applicability of Kouwen’s method. Then, a calibration of two coefficients appearing in the semilogarithmic flow resistance equation is carried out. Finally, applying the P-theorem and the incomplete self-similarity condition, a flow resistance equation linking the friction factor with the shear Reynolds number, the depth-vegetation height ratio and the inflection degree is deduced.
Testing the Stage-Discharge Relationship in Sloping SMBF Flumes
2021
The Samani, Magallanez, Baiamonte, Ferro (SMBF) flume is a simple and inexpensive instrument for indirect discharge measurement that was originally proposed for use in a horizontal channel and then also applied in sloping channels. The contraction of the flow cross section, aimed at establishing a critical flow condition, is simply obtained by applying two half cylinders to the walls of a rectangular cross section. In this paper a theoretical approach previously proposed for a horizontal SMBF flume is first extended to a sloping SMBF flume and a new stage-discharge relationship is deduced. Then, this equation is experimentally tested using laboratory measurements from literature for differe…
Explicit equations for uniform flow depth
2017
Conventional approach in uniform open channel flow is to express the resistance coefficient in the Manning, Darcy-Weisbach or Chezy form. However, for practical cross-sections, including rectangular and trapezoidal ones, the governing equation is implicit in the uniform water depth. For these sections the water depth, corresponding to known values of the flow discharge, slope channel and resistance coefficient, is presently obtained by trial and error procedure. In this paper exact analytical solutions of uniform flow depth for rectangular and trapezoidal section have been obtained in the form of fast converging power series.
Turbulence structure and coherent motion in a straight laboratory flume
2012
Evolution of coherent turbulent structures and relation with bed-forms formation in a straight flume
2008
The present paper describes some results of experimental work carried out in a rectilinear flume to investigate the interactions between flow turbulence and sediment motion. The analysis is conducted through the comparison between the periodicity of turbulent structures evolving along the channel and the wavelength of bed forms (alternate bars) forming on the bed. The occurrence of turbulent events (inward interaction, ejection, sweep and burst) has been verified through the conditioned quadrant analysis. The quantitative information about the spatial and temporal scale of the events has been obtained through the space-time correlations of the conditioned data. The analysis essentially high…
Turbulent Flow Structures For Different Roughness Conditions of Channel Walls: Results of experimental
2012
Discussion of "preliminary Study of Surface Hydraulic Jumps" by S. Ahmed, Y. Ye, H. Liu, and N. Rajaratnam
2020
In this paper the results of Preliminary Study of Surface Hydraulic Jumps” by S. Ahmed, Y. Ye, H. Liu, and N. Rajaratnam are discussed
Assessing flow resistance law in vegetated channels by dimensional analysis and self-similarity
2019
Abstract In this paper experimental data collected by Kouwen et al., Wilson and Horrit, Raffaelli et al. and Carollo et al., using straight flumes having a bed covered by grass-like vegetation with different stem concentrations, were used to analyze flow resistance for flexible submerged elements. At first, the dimensional analysis and the incomplete self-similarity hypothesis was applied to deduce the flow velocity distribution and the resulting theoretical expression of the Darcy-Weisbach friction factor. Then, a relationship between the Γ function of the velocity profile and the biomechanical characteristics of vegetation, the channel slope, the Reynolds number and the flow Froude number…
Closure to “New Theoretical Solution of Stage-Discharge Relationship for Slit Weirs” by Vito Ferro and Ismail Aydin
2018
In this paper, the flow-process of a slit weir was analyzed on the basis of a theorem of dimensional analysis and incomplete self-similarity theory. The theoretically deduced stage-discharge formula then was calibrated using experimental data obtained for a ratio between the weir and the channel width, ranging from 0.05 to 0.25. The deduced stage-discharge relationship allowed measuring discharge values characterized by errors that, for 98% of the measured values, were less than or equal to +/- 5%. The performance of the proposed theoretical stage-discharge formula also was improved by introducing the Reynolds number (for 98.5% of the measured values the error was less than or equal to +/- …
A generalized stage-discharge relationship for sharp-crested power-law weirs by dimensional analysis and self-similarity
2022
Weirs are characterized by a stage-discharge relationship which mainly depends on the shape and dimensions of the hydraulic structure. A weir with symmetrical power-law sides is a versatile weir that can produce some known weir types (rectangular, triangular, parabolic) as special cases. In this paper, the outflow process of sharp-crested power-law weirs is investigated using the dimensional analysis and the incomplete self-similarity theory. A new generalized theoretical stage-discharge relationship is proposed, and its applicability is tested using measurements available in the literature for different weir types.