RELIABILITY OF 5-BEAM LDV FIBEROPTIC PROBE FOR TURBULENCE MEASUREMENTS IN THE WALL REGION OF OPEN-CHANNEL FLOW

2009 ◽  
Vol 16 (3) ◽  
pp. 255-277 ◽  
Author(s):  
Giancarlo Alfonsi ◽  
Samuele de Bartolo ◽  
Roberto Gaudio ◽  
Leonardo Primavera
Keyword(s):  
Channel Flow ◽  
Open Channel ◽  
Open Channel Flow ◽  
Wall Region ◽  
Turbulence Measurements ◽  
Fiberoptic Probe

Discussion of “Some Turbulence Measurements in Open-Channel Flow”

1970 ◽  
Vol 96 (1) ◽  
pp. 272-276
Author(s):  
Emmanuel Partheniades ◽  
Paul H. Blinco
Keyword(s):  
Channel Flow ◽  
Open Channel ◽  
Open Channel Flow ◽  
Turbulence Measurements

Closure to “Some Turbulence Measurements in Open-Channel Flow”

1970 ◽  
Vol 96 (11) ◽  
pp. 2361-2362
Author(s):  
Raul S. McQuivey ◽  
Everett V. Richardson
Keyword(s):  
Channel Flow ◽  
Open Channel ◽  
Open Channel Flow ◽  
Turbulence Measurements

Some Turbulence Measurements in Open-Channel Flow

1969 ◽  
Vol 95 (1) ◽  
pp. 209-224
Author(s):  
R. S. McQuivey ◽  
E. V. Richardson
Keyword(s):  
Channel Flow ◽  
Open Channel ◽  
Open Channel Flow ◽  
Turbulence Measurements

Discussion of “Some Turbulence Measurements in Open-Channel Flow”

1970 ◽  
Vol 96 (1) ◽  
pp. 272-276
Author(s):  
Emmanuel Partheniades ◽  
Paul H. Blinco
Keyword(s):  
Channel Flow ◽  
Open Channel ◽  
Open Channel Flow ◽  
Turbulence Measurements

Closure to “Some Turbulence Measurements in Open-Channel Flow”

1970 ◽  
Vol 96 (11) ◽  
pp. 2361-2362
Author(s):  
Raul S. McQuivey ◽  
Everett V. Richardson
Keyword(s):  
Channel Flow ◽  
Open Channel ◽  
Open Channel Flow ◽  
Turbulence Measurements

Experiments on particle—turbulence interactions in the near–wall region of an open channel flow: implications for sediment transport

1996 ◽  
Vol 326 ◽  
pp. 285-319 ◽  
Author(s):  
Y. Ninto ◽  
M. H. Garcia
Keyword(s):  
Flow Velocity ◽  
Channel Flow ◽  
Open Channel ◽  
Vertical Component ◽  
Open Channel Flow ◽  
Viscous Sublayer ◽  
Wall Region ◽  
Mean Flow ◽  
Sediment Particles ◽  
Near Wall

A high-speed video system was used to study the interaction between sediment particles and turbulence in the wall region of an open channel flow with both smooth and transitionally rough beds. In smooth flows, particles immersed within the viscous sublayer were seen to accumulate along low-speed wall streaks; apparently due to the presence of quasi-streamwise vortices in the wall region. Larger particles did not tend to group along streaks, however their velocity was observed to respond to the streaky structure of the flow velocity in the wall region. In transitionally rough flows particle sorting was not observed. Coherent flow structures in the form of shear layers typically observed in the near-wall region interacted with sediment particles lying on the channel bottom, resulting in the particles being entrained into suspension. Although there has been some speculation that this process would not be effective in entraining particles totally immersed in the viscous sublayer, the results obtained demonstrate the opposite. The entrainment mechanism appears to be the same independent of the roughness condition of the bottom wall, smooth or transitionally rough. In the latter case, however, hiding effects tend to preclude the entrainment of particles with sizes finer than that of the roughness elements. The analysis of particle velocity during entrainment shows that the streamwise component tends to be much smaller than the local mean flow velocity, while the vertical component tends to be much larger than the local standard deviation of the vertical flow velocity fluctuations, which would indicate that such particles are responding to rather extreme flow ejection events.

Experimental study on the coherent structure of turbulent open-channel flow using visualization and picture processing

1987 ◽  
Vol 174 ◽  
pp. 399-440 ◽  
Author(s):  
Tadashi Utami ◽  
Tetsuo Ueno
Keyword(s):  
Flow Visualization ◽  
Channel Flow ◽  
Coherent Structure ◽  
Open Channel ◽  
Open Channel Flow ◽  
Wall Region ◽  
Turbulence Structure ◽  
Two Dimensional ◽  
Picture Processing ◽  
Three Components

Coherent structures of turbulent open-channel flow in the wall region of a channel bed were examined quantitatively using experimental data obtained by flow visualization. Successive pictures of flow patterns in two horizontal cross-sections at different levels near the channel bed were taken, and then were digitized and analysed by a computer.This method of flow visualization and picture processing enabled us to calculate the distributions of the three components of the velocity vectors. The distributions of velocities, streamlines, two-dimensional divergence and three components of vorticity could be calculated and are displayed as graphical output. In our numerical analyses, the idea of a two-dimensional correlation coefficient is introduced, through which the degree of similarity of turbulence structures can be better estimated than with the usual one-dimensional coefficient. Use of the data was based on the premise that the essential element in a turbulence structure is vortex motion.We propose a conceptual model of turbulence structure in which the elementary unit of coherent structure in the buffer layer is presumed to be a horseshoe vortex and in which the characteristics of the multiple structure of turbulence are shown with respect to the scale, arrangement and generating process of horseshoe vortices and longitudinal vortices. Our model clearly explains the generating mechanism and mutual relations of low-speed regions, high-speed regions, ejections, sweeps and localized free-shear layers.

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