scholarly journals Air-water flow properties in breaking bores and stationary jumps with the same Froude number - analogies and dissimilarities

2020 ◽  
Author(s):  
Davide Wuthrich ◽  
Rui Shi ◽  
Hubert Chanson
Keyword(s):  
Froude Number ◽  
Water Flow ◽  
Flow Properties

scholarly journals The conditions for occurrence of critical flow regime of water in the open stream

2019 ◽  
Vol 97 ◽  
pp. 05006
Author(s):  
Yuliya Bryanskaya ◽  
Aleksandra Ostiakova
Keyword(s):  
Froude Number ◽  
Flow Regime ◽  
Water Flow ◽  
Practical Interest ◽  
Open Water ◽  
Critical Regime ◽  
Critical Flow ◽  
Channel Processes ◽  
Channel Deformations ◽  
Critical Flow Regime

For the solution of engineering problems require increasingly accurate estimates of the hydraulic characteristics of the water streams. To date, it is impossible to consider sufficiently complete theoretical and experimental justification of the main provisions of the theory of turbulence, hydraulic resistance, channel processes. The composition of tasks related to flows in wide channels, turbulence problems are of scientific and practical interest. Various interpretations of the determination of the critical Froude number in wide open water flows based on observations and theoretical transformations are considered. The conditions for the emergence of a critical regime of water flow in an open wide channel are analyzed in order to estimate the critical Froude number and critical depth. Estimates of the critical Froude number for laboratory and field conditions are given. The estimations allow us to consider the proposed approach acceptable for determining the conditions of occurrence of the critical flow regime. The General, physical interpretation of conditions of occurrence of the critical regime of water flow on the basis of phenomenological approach is specified. The results take into account the values of the components of the total specific energy of the section. This shows the estimated calculation. The results obtained theoretically make it possible to compare the above interpretations and determine their applicability, and the results of the analysis can be useful for the estimated calculations of flows in channels and river flows in rigid, undeformable boundaries and with minor channel deformations.

On the applicability of Washburn law: study of mercury and water flow properties in cement-based materials

2004 ◽  
Vol 37 (2) ◽  
pp. 107-113 ◽  
Author(s):  
A. Aït-Mokhtar ◽  
O. Amiri ◽  
P. Dumargue ◽  
A. Bouguerra
Keyword(s):  
Water Flow ◽  
Flow Properties ◽  
Cement Based Materials

scholarly journals Experimental investigations of air entrainment in transition and skimming flows down a stepped chute

2002 ◽  
Vol 29 (1) ◽  
pp. 145-156 ◽  
Author(s):  
H Chanson ◽  
L Toombes
Keyword(s):  
Free Surface ◽  
Water Flow ◽  
Air Entrainment ◽  
Stepped Spillway ◽  
Transition Flow ◽  
Flow Properties ◽  
Flow Measurements ◽  
Surface Aeration ◽  
Stepped Chute ◽  
Uniform Equilibrium

Stepped spillways have been used for about 3500 years. The last few decades have seen the development of new construction materials, design techniques, and applications, for example, embankment overtopping protection systems. Although it is commonly acknowledged that free-surface aeration is significant in stepped chutes, experimental data are scarce, often limited to very steep slopes (α ~ 50°). This paper presents an experimental study conducted in a large-size stepped chute (α = 22°, h = 0.1 m, W = 1 m). Observations demonstrate the existence of a transition flow pattern for intermediate flow rates between nappe and skimming flows. Detailed air–water flow measurements were conducted in both transition and skimming flows, immediately downstream of the inception point of free-surface aeration where uniform equilibrium flow conditions were not achieved. In skimming flows, a complete characterization is developed for the distributions of void fraction, bubble count rate, and velocity, and flow resistance data are compared with other studies. Transition flows exhibit significantly different air–water flow properties. They are highly aerated, requiring the design of comparatively high chute sidewalls.Key words: stepped spillway, air entrainment, two-phase flow properties, skimming flow, transition flow.

Air-Water Flow Properties in Hydraulic Jumps with Fully and Partially Developed Inflow Conditions

2021 ◽  
Author(s):  
Laura Montano ◽  
Stefan Felder
Keyword(s):  
Water Flow ◽  
Flow Patterns ◽  
Hydraulic Jumps ◽  
Clear Water ◽  
Flow Properties ◽  
Flow Measurements ◽  
Void Fractions ◽  
Bubble Sizes ◽  
Sampling Duration ◽  
Inflow Conditions

Abstract Novel air-water flow measurements were conducted in fully aerated hydraulic jumps with partially and fully developed supercritical inflow conditions. Irrespective of the inflow conditions, the hydraulic jumps resembled typical flow patterns with strong aeration and instabilities, albeit hydraulic jumps with fully developed inflow conditions had a more upwards directed roller motion and a larger clear water core in the second half of the roller. Hydraulic jumps with fully developed inflow conditions had comparatively larger void fractions in the first half of the jump roller and larger bubble count rates throughout, while a comparatively larger number of smaller bubble sizes suggested a stronger break-up of bubbles. This was consistent with slightly larger interfacial velocities and turbulence intensities in the first half of the jump roller with fully developed inflow conditions. An assessment of the required sampling duration for air-water flow properties indicated the requirement to sample for at least five times longer duration than applied in previous studies. These results highlighted the need to carefully consider the inflow conditions and sampling parameters for aerated hydraulic jumps.

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