scholarly journals Free Surface Length Scale Estimation in Hydraulic Jumps

2005 ◽  
Vol 127 (6) ◽  
pp. 1191-1193 ◽  
Author(s):  
D. Mouaze ◽  
F. Murzyn ◽  
J. R. Chaplin
Keyword(s):  
Free Surface ◽  
Cross Correlation ◽  
Mixing Layer ◽  
Hydraulic Jumps ◽  
Similar Data ◽  
Two Phase ◽  
Length Scales ◽  
Phase Measurements ◽  
Cross Correlation Analysis ◽  
Surface Length

In the context of recent work by Brocchini and Peregrine [J. Fluid Mech., 449, pp. 225–254 (2001a); 449, pp. 255–290 (2001b)] in this paper we aim to document free surface elevations and free surface length scales in hydraulic jumps with Froude numbers between 1.98 and 4.82. Although information on bubble size, frequency, and velocities in hydraulic jumps is available in the literature, there is not much data on the features of the free surface, or on mixing layer thickness. In the present case, measurements at the free surface have been realized with two “homemade” miniature resistive wire gauges made of two parallel 50μm diameter wires 1mm apart. These instruments were calibrated dynamically over a range of frequencies up to 20Hz. The present results extend the range of Froude numbers for which two-phase measurements in hydraulic jumps are available. In most respects, it confirms earlier results obtained with different experimental techniques. Length scales at the free surface are deduced from a cross-correlation analysis of wire gauge measurements, and are compared with similar data obtained from images of the surface.

scholarly journals Turbulence at Free Surface in Hydraulic Jumps

Volume 1 ◽  
2004 ◽  
Author(s):  
D. Mouaze ◽  
F. Murzyn ◽  
J. R. Chaplin
Keyword(s):  
Free Surface ◽  
Mixing Layer ◽  
Hydraulic Jumps ◽  
Similar Data ◽  
Two Phase ◽  
Length Scales ◽  
Phase Measurements ◽  
Void Fractions ◽  
Cross Correlation Analysis ◽  
Turbulence Length

In the context of recent work by Brocchini & Peregrine [1,2], this paper aims to document free surface profiles, and turbulence length scales in hydraulic jumps with Froude numbers between 1.98 and 4.82. Although information on bubble size, frequency and velocities in hydraulic jumps is available in the literature, there is not much data on the features of the free surface, or on mixing layer thickness. In the present case, measurements at the free surface have been realized with two miniature resistive wire gauges each comprising two parallel 50 micron diameter wires with a separation of 1mm. These instruments were calibrated dynamically over a range of frequencies up to 20 Hz. Furthermore optical probes were used to measure properties of the air phase within the jump, including void fractions (up to 98%). The present results extend the range of Froude numbers for which two-phase measurements in hydraulic jumps are available, and, in most respects, confirm earlier results obtained with different experimental techniques. Length scales at the free surface are deduced from cross-correlation analysis of wire gauge measurements, and are compared with similar data obtained from images of the surface.

Sound transmission in the lung as a function of lung volume

2002 ◽  
Vol 93 (2) ◽  
pp. 667-674 ◽  
Author(s):  
T. Bergstresser ◽  
D. Ofengeim ◽  
A. Vyshedskiy ◽  
J. Shane ◽  
R. Murphy
Keyword(s):  
Transit Time ◽  
Lung Volume ◽  
Cross Correlation ◽  
Sound Transmission ◽  
Phase System ◽  
Two Phase ◽  
Tissue Properties ◽  
Air Content ◽  
Transit Times ◽  
Cross Correlation Analysis

We were interested in how the transmission of sound through the lung was affected by varying air content in intact humans as a method of monitoring tissue properties noninvasively. To study this, we developed a method of measuring transthoracic sound transit time accurately. We introduced a “coded” sound at the mouth and measured the transit time at multiple microphones placed over the chest wall by using a 16-channel lung sound analyzer (Stethographics). We used a microphone placed over the neck near the trachea as our reference and utilized cross-correlation analysis to calculate the transit times. The use of the coded sound, composed of a mix of frequencies from 130 to 150 Hz, greatly reduced the ambiguity of the cross-correlation function. The measured transit time varied from 1 ms at the central locations to 5 ms at the lung bases. Our results also indicated that transit time at all locations decreased with increasing lung volume. We found that these results can be described in terms of a model in which sound transmission through the lung is treated as a combination of free-space propagation through the trachea and a propagation through a two-phase system in the parenchyma.

Measurements of single-phase and two-phase flows in a vertical pipe using ultrasonic pulse Doppler method and ultrasonic time-domain cross-correlation method

2013 ◽  
Vol 35 (3) ◽  
Author(s):  
Tat Thang Nguyen ◽  
Hiroshige Kikura ◽  
Ngoc Hai Duong ◽  
Hideki Murakawa ◽  
Nobuyoshi Tsuzuki
Keyword(s):  
Time Domain ◽  
Cross Correlation ◽  
Single Phase ◽  
Ultrasonic Pulse ◽  
Phase Flow ◽  
Beam Diameter ◽  
Vertical Pipe ◽  
Two Phase ◽  
Ultrasonic Time ◽  
Pulse Doppler

Ultrasonic Velocity Profile (UVP) method for measurement of single-phase and two-phase flow in a vertical pipe has recently been developed in the Laboratory for industrial and Environmental Fluid Dynamics, Institute of Mechanics, VAST. The signal processings of the UVP method include the ultrasonic pulse Doppler method (UDM)and the ultrasonic time-domain cross-correlation (UTDC) method. For two-phase flow, simultaneous measurements of both liquid and gas are enabled by using a multi-wave ultrasonic transducer (multi-wave TDX). The multi-wave TDX is able to emit and receive ultrasound of two different center frequencies of 2 MHz and 8 MHz at the same time and position. 2 MHz frequency with beam diameter 10 mm is exploited for measurement of gas. 8 MHz one with beam diameter 3 mm is used for liquid. Measurements have been carried out for laminar and turbulent single-phase flows and bubbly counter-current two-phase flows in two flow loops using two vertical pipes of 26 mm inner diameter (I.D.) and 50 mm I.D. respectively. Based on the measured results, assessment of each method is clarified. Applicability of each method for different conditions of pipe flow has been tested. Suggestions for application of the two methods have been recommended.

Application of Cross-correlation Analysis Method for Measurement of the Fluid Flow Rate Based on X-ray Radiation

2019 ◽  
Vol 11 (1) ◽  
pp. 01025-1-01025-5 ◽  
Author(s):  
N. A. Borodulya ◽  
◽  
R. O. Rezaev ◽  
S. G. Chistyakov ◽  
E. I. Smirnova ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Correlation Analysis ◽  
Flow Rate ◽  
Cross Correlation ◽  
Fluid Flow Rate ◽  
Analysis Method ◽  
X Ray ◽  
Cross Correlation Analysis ◽  
Correlation Analysis Method
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