Structure of Temperature Fluctuations in the Turbulent Wake behind a Heated Cylinder

1971 ◽  
Vol 14 (12) ◽  
pp. 2574 ◽  
Author(s):  
Peter Freymuth
Keyword(s):  
Temperature Fluctuations ◽  
Turbulent Wake ◽  
Heated Cylinder

Conditional sampling study of the turbulent wake of a cylinder. Part 1

1979 ◽  
Vol 94 (4) ◽  
pp. 673-709 ◽  
Author(s):  
Gracio Fabris
Keyword(s):  
Digital Processing ◽  
Turbulent Wake ◽  
Temperature Fields ◽  
Stream Velocity ◽  
Temperature Threshold ◽  
Turbulence Structure ◽  
Potential Zone ◽  
Heated Cylinder ◽  
Accuracy Of Results ◽  
Physical Phenomena

The far turbulent wake of a slightly heated cylinder was studied using our specially developed four-wire probe and digital processing of signals obtained. The processing method included a simultaneous solution of full nonlinear response equations for the four sensors yielding values of instantaneous velocity vector and temperature. The accuracy of results was improved substantially by the subtraction of free-stream velocity and temperature variations, first-order corrections for the d.c. drift of the signals, the elimination of 60 Hz related noise, and instantaneous correction for the streamwise displacement between the sensor wires. A low temperature threshold was used to discriminate between turbulent and potential flow.The frequency of crossing of the turbulent-potential interface and statistics of turbulent and potential zone intervals are presented. Conditionally sampled fluctuating velocity and temperature fields are given for turbulent and potential zones as well as for a fluid at the downstream and upstream interface of the turbulent zones. Averaging was done with respect to conventional (Reynolds) as well as local zone or point means. The results on turbulence structure up to second-order correlations are presented in this paper.It is hoped that the data will be useful for those interested in methods of prediction of turbulence, especially those based on the consideration of large structures. Researchers more interested in the physical phenomena involved might also find the data suitable for further analysis and interpretation.

Detailed similarity in the turbulent wake of a heated cylinder

1978 ◽  
Vol 21 (6) ◽  
pp. 891 ◽  
Author(s):  
John C. LaRue ◽  
Paul A. Libby
Keyword(s):  
Turbulent Wake ◽  
Heated Cylinder

Refined similarity hypotheses for passive scalars mixed by turbulence

1995 ◽  
Vol 297 ◽  
pp. 275-291 ◽  
Author(s):  
G. Stolovitzky ◽  
P. Kailasnath ◽  
K. R. Sreenivasan
Keyword(s):  
Large Scale ◽  
Temperature Fluctuations ◽  
Scalar Fields ◽  
Reynolds Numbers ◽  
Passive Scalar ◽  
Local Isotropy ◽  
Passive Scalars ◽  
Heated Cylinder ◽  
Conditional Expectations ◽  
High Reynolds

In analogy with Kolmogorov's refined similarity hypotheses for the velocity field, two hypotheses are stated for passive scalar fields mixed by high-Reynolds-number turbulence. A ‘refined’ Yaglom equation is derived under the new assumption of local isotropy in pure ensembles, which is stronger than the usual assumption of local isotropy but weaker than the isotropy of the large scale. The new theoretical result is shown to be consistent with the hypotheses of refined similarity for passive scalars. These hypotheses are approximately verified by experimental data on temperature fluctuations obtained (in air) at moderate Reynolds numbers in the wake of a heated cylinder. The fact that the refined similarity hypotheses are stated for high Reynolds (and Péclet) numbers, but verified at moderate Reynolds (and Péclet) numbers suggests that these hypotheses are not sufficiently sensitive tests of universality. It is conjectured that possible departures from universality are hidden by the process of taking conditional expectations.

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