scholarly journals Simultaneous Eulerian–Lagrangian velocity measurements of particulate pipe flow in transitional regime

2020 ◽  
Vol 91 (9) ◽  
pp. 095110
Author(s):  
S. Singh ◽  
A. Pothérat ◽  
C. C. T. Pringle ◽  
I. R. J. Bates ◽  
Martin Holdsworth
Keyword(s):  
Pipe Flow ◽  
Velocity Measurements ◽  
Transitional Regime ◽  
Lagrangian Velocity

Velocity measurements made with a laser dopplermeter on the turbulent pipe flow of a dilute polymer solution

1972 ◽  
Vol 51 (4) ◽  
pp. 673-685 ◽  
Author(s):  
M. J. Rudd
Keyword(s):  
Polymer Solution ◽  
Velocity Component ◽  
Pipe Flow ◽  
Viscous Sublayer ◽  
Turbulent Pipe Flow ◽  
Velocity Measurements ◽  
Velocity Fluctuations ◽  
Conventional Models ◽  
Drag Reducing Polymer ◽  
Spanwise Velocity

This paper presents some new measurements which have been made on a drag-reducing polymer solution in pipe flow. A novel type of laser dopplermeter, which has been developed by the author, is briefly described and the measurements which have been obtained are given. These results and their implications are then discussed in terms of conventional models for turbulent flow in a pipe. These suggest that the polymer has very little effect upon the turbulent core of the flow, but thickens and stabilizes the viscous sublayer. The turbulent intensity inside the sublayer is unchanged but, owing to its thickening, the velocity fluctuations just outside are greater. There is not a general suppression of turbulence within the sublayer although well inside the sublayer the spanwise velocity component is found to be reduced.

scholarly journals Laminar–Turbulent Intermittency in Annular Couette–Poiseuille Flow: Whether a Puff Splits or Not

Entropy ◽  
2020 ◽  
Vol 22 (12) ◽  
pp. 1353
Author(s):  
Hirotaka Morimatsu ◽  
Takahiro Tsukahara
Keyword(s):  
Poiseuille Flow ◽  
Pipe Flow ◽  
Large Scale ◽  
Outer Cylinder ◽  
Base Flow ◽  
Circular Pipe ◽  
Turbulence Structure ◽  
Transitional Regime ◽  
Circular Pipe Flow ◽  
Observation Period

Direct numerical simulations were carried out with an emphasis on the intermittency and localized turbulence structure occurring within the subcritical transitional regime of a concentric annular Couette–Poiseuille flow. In the annular system, the ratio of the inner to outer cylinder radius is an important geometrical parameter affecting the large-scale nature of the intermittency. We chose a low radius ratio of 0.1 and imposed a constant pressure gradient providing practically zero shear on the inner cylinder such that the base flow was approximated to that of a circular pipe flow. Localized turbulent puffs, that is, axial uni-directional intermittencies similar to those observed in the transitional circular pipe flow, were observed in the annular Couette–Poiseuille flow. Puff splitting events were clearly observed rather far from the global critical Reynolds number, near which given puffs survived without a splitting event throughout the observation period, which was as long as 104 outer time units. The characterization as a directed-percolation universal class was also discussed.

Spectral Vorticity and Lagrangian Velocity Measurements in Turbulent Jets

2004 ◽  
Vol 72 (2-4) ◽  
pp. 245-271 ◽  
Author(s):  
Cedric Poulain ◽  
Nicolas Mazellier ◽  
Philippe Gervais ◽  
Yves Gagne ◽  
Christophe Baudet
Keyword(s):  
Turbulent Jets ◽  
Velocity Measurements ◽  
Lagrangian Velocity

scholarly journals Experimental Study of the Flow in a Compact Heat Exchanger Channel With Embossed-Type Vortex Generators

2003 ◽  
Vol 125 (4) ◽  
pp. 701-709 ◽  
Author(s):  
F. Dupont ◽  
C. Gabillet ◽  
P. Bot
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Vortex Generators ◽  
Compact Heat Exchanger ◽  
Velocity Measurements ◽  
Transfer Enhancement ◽  
Transitional Regime ◽  
Longitudinal Vortices ◽  
Flow Features ◽  
Model Channel

The isothermal flow in a model channel of plate-fin heat exchanger with periodically arranged embossed-like vortex generators is investigated. Velocity measurements are performed by LDA in the transitional regime (Reynolds number from 1000 up to 5000). Strong longitudinal vortices are observed downstream of each generator. The vortex rollup process is highlighted by the evolution of the velocity vector field in the cross section of the flow. The modifications of the vortex characteristics after successively encountered generators are investigated. This work shows most of the flow features which are known to produce heat transfer enhancement, and shows that these smooth shaped vortex generators are very promising for enhanced heat exchangers.

Experimental Determination of Lagrangian Velocity Statistics in Turbulent Pipe Flow

2006 ◽  
Vol 76 (2) ◽  
pp. 163-175 ◽  
Author(s):  
R. J. E. Walpot ◽  
J. G. M. Kuerten ◽  
C. W. M. van der Geld
Keyword(s):  
Experimental Determination ◽  
Pipe Flow ◽  
Turbulent Pipe Flow ◽  
Velocity Statistics ◽  
Lagrangian Velocity
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