Intrusive and Non-intrusive Air-water Flow Measurements in Breaking Jumps at Low Froude Number and Large Reynolds Number

2021 ◽  
Author(s):  
Rui Shi ◽  
Davide Wüthrich ◽  
Hubert Chanson
Keyword(s):  
Reynolds Number ◽  
Froude Number ◽  
Water Flow ◽  
Large Reynolds Number ◽  
Flow Measurements ◽  
Low Froude Number

Regeneration of turbulent fluctuations in low-Froude-number flow over a sphere at a Reynolds number of 3700

2016 ◽  
Vol 804 ◽  
Author(s):  
Anikesh Pal ◽  
Sutanu Sarkar ◽  
Antonio Posa ◽  
Elias Balaras
Keyword(s):  
Reynolds Number ◽  
Froude Number ◽  
Qualitative Change ◽  
Turbulence Energy ◽  
Horizontal Shear ◽  
Near Wake ◽  
Turbulent Fluctuations ◽  
Flow Past ◽  
Low Froude Number ◽  
Flow Past A Sphere

Direct numerical simulations (DNS) are performed to study the behaviour of flow past a sphere in the regime of high stratification (low Froude number $Fr$). In contrast to previous results at lower Reynolds numbers, which suggest monotone suppression of turbulence with increasing stratification in flow past a sphere, it is found that, below a critical $Fr$, increasing the stratification induces unsteady vortical motion and turbulent fluctuations in the near wake. The near wake is quantified by computing the energy spectra, the turbulence energy equation, the partition of energy into horizontal and vertical components, and the buoyancy Reynolds number. These diagnostics show that the stabilizing effect of buoyancy changes flow over the sphere to flow around the sphere. This qualitative change in the flow leads to a new regime of unsteady vortex shedding in the horizontal planes and intensified horizontal shear which result in turbulence regeneration.

On the Inflow Phenomenon in Near Field of Buoyant Jet at Low Froude Number

2012 ◽  
Author(s):  
Atsushi Maeda ◽  
Takayuki Yamagata ◽  
Nobuyuki Fujisawa
Keyword(s):  
Reynolds Number ◽  
Froude Number ◽  
Near Field ◽  
Quantitative Information ◽  
Experimental Result ◽  
Inflow Rate ◽  
Buoyant Jet ◽  
Square Duct ◽  
Wide Range ◽  
Low Froude Number

In the present paper, the inflow phenomenon in the near-field of a buoyant jet issuing from a square duct is studied by using scanning LIF and scanning PIV measurements. The scanning LIF visualization allows an insight into the critical condition of the inflow phenomenon in a wide range of Froude number and Reynolds number. While, the scanning PIV allows the quantitative information on the inflow rate through the duct exit. The experimental result shows that the critical Froude number increases with an increase in Reynolds number in the duct exit up to Reynolds number 2,000, though it is weakened at higher Reynolds number. The examination of the inflow rate indicates that the large magnitude of the inflow rate occurs in the lower Froude number and Reynolds number.

Two-phase air-water flow properties in hydraulic jump at low froude number: Scale effects in physical modelling

2021 ◽  
Author(s):  
Jorge Estrella ◽  
Davide Wuthrich ◽  
Hubert Chanson
Keyword(s):  
Froude Number ◽  
Water Flow ◽  
Hydraulic Jump ◽  
Scale Effects ◽  
Physical Modelling ◽  
Flow Properties ◽  
Two Phase ◽  
Low Froude Number

Investigation of the influence of the flow structure on the accuracy of flow measurement before a hydrometric structure in an open channel

2020 ◽  
pp. 41-44
Author(s):  
Anatoly Kusher
Keyword(s):  
Velocity Profile ◽  
Flow Velocity ◽  
Water Flow ◽  
Flow Measurement ◽  
Water Discharge ◽  
Critical Depth ◽  
Flow Measurements ◽  
Study Results ◽  
Flow Velocity Profile ◽  
Upstream Flow

The reliability of water flow measurement in irrigational canals depends on the measurement method and design features of the flow-measuring structure and the upstream flow velocity profile. The flow velocity profile is a function of the channel geometry and wall roughness. The article presents the study results of the influence of the upstream flow velocity profile on the discharge measurement accuracy. For this, the physical and numerical modeling of two structures was carried out: a critical depth flume and a hydrometric overfall in a rectangular channel. According to the data of numerical simulation of the critical depth flume with a uniform and parabolic (1/7) velocity profile in the upstream channel, the values of water discharge differ very little from the experimental values in the laboratory model with a similar geometry (δ < 2 %). In contrast to the critical depth flume, a change in the velocity profile only due to an increase in the height of the bottom roughness by 3 mm causes a decrease of the overfall discharge coefficient by 4…5 %. According to the results of the numerical and physical modeling, it was found that an increase of backwater by hydrometric structure reduces the influence of the upstream flow velocity profile and increases the reliability of water flow measurements.

CORRELATION FOR CONVECTIVE HEAT TRANSFER IN TURBULENT PULSATING FLOW AT LARGE REYNOLDS NUMBER INSIDE CIRCULAR PIPE

2012 ◽  
Vol 19 (2) ◽  
pp. 149-159
Author(s):  
Hua Li ◽  
Yingjie Zhong ◽  
Kai Deng ◽  
Zangjian Yang ◽  
Yanjun Hu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Pulsating Flow ◽  
Circular Pipe ◽  
Large Reynolds Number

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.

An example of steady laminar flow at large Reynolds number

1960 ◽  
Vol 9 (4) ◽  
pp. 593-602 ◽  
Author(s):  
Iam Proudman
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Boundary Layers ◽  
Tangential Velocity ◽  
Fluid Flows ◽  
The Other ◽  
Large Reynolds Number ◽  
Rotational Flows ◽  
Flow Domain ◽  
Source Of Information

The purpose of this note is to describe a particular class of steady fluid flows, for which the techniques of classical hydrodynamics and boundary-layer theory determine uniquely the asymptotic flow for large Reynolds number for each of a continuously varied set of boundary conditions. The flows involve viscous layers in the interior of the flow domain, as well as boundary layers, and the investigation is unusual in that the position and structure of all the viscous layers are determined uniquely. The note is intended to be an illustration of the principles that lead to this determination, not a source of information of practical value.The flows take place in a two-dimensional channel with porous walls through which fluid is uniformly injected or extracted. When fluid is extracted through both walls there are boundary layers on both walls and the flow outside these layers is irrotational. When fluid is extracted through one wall and injected through the other, there is a boundary layer only on the former wall and the inviscid rotational flow outside this layer satisfies the no-slip condition on the other wall. When fluid is injected through both walls there are no boundary layers, but there is a viscous layer in the interior of the channel, across which the second derivative of the tangential velocity is discontinous, and the position of this layer is determined by the requirement that the inviscid rotational flows on either side of it must satisfy the no-slip conditions on the walls.

Thermally Forced Low Froude Number Flow past Three-Dimensional Obstacles

1994 ◽  
Vol 51 (1) ◽  
pp. 117-133 ◽  
Author(s):  
Jon M. Reisner ◽  
Piotr K. Smolarkiewicz
Keyword(s):  
Froude Number ◽  
Three Dimensional ◽  
Flow Past ◽  
Low Froude Number ◽  
Number Flow

Further Results on Lee Vortices in Low-Froude-Number Flow

1991 ◽  
Vol 48 (19) ◽  
pp. 2204-2211 ◽  
Author(s):  
Richard Rotunno ◽  
Piotr K. Smolarkiewicz
Keyword(s):  
Froude Number ◽  
Low Froude Number ◽  
Number Flow
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