scholarly journals An experimental investigation and statistical analysis of turbulent swirl flow in a straight pipe

2017 ◽  
Vol 21 (suppl. 3) ◽  
pp. 691-704 ◽  
Author(s):  
Milan Lecic ◽  
Aleksandar Cocic ◽  
Jela Burazer
Keyword(s):  
Velocity Field ◽  
Turbulent Transport ◽  
Field Measurements ◽  
Viscous Sublayer ◽  
Swirl Flow ◽  
Transport Processes ◽  
Statistical Characteristics ◽  
Straight Pipe ◽  
Measured Velocity ◽  
Swirl Flows

This paper presents results of our own velocity field measurements in a straight pipe swirl flow. These studies were conducted using an originally designed hot wire probe. Due to the specially tailored shape of the probe, it was possible to get four measurement points in the viscous sublayer. The time-averaged velocity field and the statistical moments of the second and third order are calculated based on the measured velocity components. Mathematical and physical interpretations of statistical characteristics and structures of turbulent swirl flow in the time domain are presented. On the basis of these results, deeper insight into turbulent transport processes can be obtained, as well as useful conclusions necessary for turbulent swirl flows modeling.

scholarly journals Oscillating grids turbulence generator for turbulent transport studies

2002 ◽  
Vol 9 (3/4) ◽  
pp. 201-205 ◽  
Author(s):  
A. Eidelman ◽  
T. Elperin ◽  
A. Kapusta ◽  
N. Kleeorin ◽  
A. Krein ◽  
...  
Keyword(s):  
Velocity Field ◽  
Large Scale ◽  
Turbulent Transport ◽  
Observation Time ◽  
Statistical Characteristics ◽  
Small Scale ◽  
Flow Measurements ◽  
Oscillating Grids ◽  
Set Up ◽  
Turbulence Generator

Abstract. An oscillating grids turbulence generator was constructed for studies of two new effects associated with turbulent transport of particles, turbulent thermal diffusion and clustering instability. These effects result in formation of large-scale and small-scale inhomogeneities in the spatial distribution of particles. The advantage of this experimental set-up is the feasibility to study turbulent transport in mixtures with controllable composition and unlimited observation time. For flow measurements we used Particle Image Velocimetry with the adaptive multi-pass algorithm to determine a turbulent velocity field and its statistical characteristics. Instantaneous velocity vector maps, flow streamlines and probability density function of velocity field demonstrate properties of turbulence generated in the device.

Laboratory studies of the velocity field over deep-water waves

1970 ◽  
Vol 42 (4) ◽  
pp. 733-754 ◽  
Author(s):  
Robert H. Stewart
Keyword(s):  
Velocity Field ◽  
Deep Water ◽  
Water Waves ◽  
Numerical Solutions ◽  
Viscous Sublayer ◽  
Reynolds Stresses ◽  
Mean Velocity ◽  
Measured Velocity ◽  
The Mean ◽  
Deep Water Waves

The mean-velocity field over monochromatic, 1·96 Hz, deep-water waves was measured by means of hot-wire anemometers for a range of wind speeds (relative to wave speed) of 0·4 to 3·0. The mean-velocity profile, over waves 0·64 cm in amplitude, was the same as that over a rough plate; that is, the mean velocity varied as the logarithm of the height above the mean-water level, except very close to the water, where the effect of the viscous sublayer became important. The wave-induced perturbation-velocity field and its associated Reynolds stresses were also measured and compared with numerical solutions of various linear equations governing shearing flow over a wavy boundary. The comparison showed that the measured velocity field was not well predicted by these theories.

CONSIDERATION OF THE VALIDITY OF THE STATISTICAL CHARACTERISTICS OF pH IN SURFACE WATERS

2019 ◽  
Vol 13 (2) ◽  
pp. 52-58
Author(s):  
V. B. Korobov ◽  
I. V. Miskevich ◽  
A. S. Lokhov ◽  
K. A. Seredkin
Keyword(s):  
Field Measurements ◽  
Heavy Precipitation ◽  
The State ◽  
Statistical Characteristics ◽  
Mean Values ◽  
River Waters ◽  
Ph Values ◽  
State Of Water ◽  
Environment Temperature ◽  
Unit Characteristic

Abstract: pH is one of the most important parameters characterizing the state of water systems. The arithmetic mean values of samples are often used when averaging serial pH measurements in water bodies, as is usually done for other characteristics of the state of the natural environment (temperature, salinity, oxygen concentrations, suspended solids, etc.). However, in this case such an operation is illegal, since the addition of logarithms, which by definition are pH, is non-additive. The authors conducted a study to determine the extent to which pH variability in natural objects such an operation would not distort the results. For this, several samples of the pH index were generated in various ranges of its theoretically possible and natural variability. It was established that with pH variability of less than a unit characteristic of marine pH values, the statistical characteristics of the indicator and [H+ ] concentrations differ slightly, and the medians of the samples coincide. It is concluded that with such ranges characteristic of the waters of the oceans, there is no need to recalculate previously obtained results. However, for the estuaries of rivers flowing into tidal seas, as shown by field measurements, the pH variability in the mixing zone of sea and river waters is several times higher. Similar situations may occur when heavy precipitation falls on the water surface, as well as during floods. In these cases, a simple averaging of the pH values will no longer be correct. In such cases, the use of other averaging algorithms and the choice of stable statistical characteristics are required.

Velocity field measurements of a laminar thermal

1979 ◽  
Vol 22 (6) ◽  
pp. 1044 ◽  
Author(s):  
D. J. Shlien ◽  
A. Brosh
Keyword(s):  
Velocity Field ◽  
Field Measurements
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