Details
| Original language | English |
|---|---|
| Article number | 075108 |
| Journal | Physics of fluids |
| Volume | 23 |
| Issue number | 7 |
| Early online date | 21 Jul 2011 |
| Publication status | Published - 27 Jul 2011 |
| Externally published | Yes |
Abstract
Measurements of instantaneous velocity fields in the separated flow downstream of a backward-facing step in a rotating channel are presented for the first time. Particle image velocimetry (PIV) measurements were made for 13 different rotation numbers Ro at a bulk flow Reynolds number of about 5600. The expansion ratio 2:1 was the same as in the flow visualization study by Rothe and Johnston [ASME J. Fluids Eng. 101, 117 (1979)] which covered about the same range of Ro. The measured mean flow pattern exhibited substantial variations with the rate of system rotation. In particular, the length of the primary separation bubble decreased monotonically with increasing anti-cyclonic rotation and increased with increasing rate of cyclonic rotation, in keeping with the earlier observations. At the highest anti-cyclonic rotation rate, the flow field also separated from the planar wall where the shear layer flow was subjected to cyclonic rotation. The PIV data for the in-plane components of the Reynolds stress tensor were severely affected by the imposed system rotation. Almost all the striking affects of the Coriolis force observed herein could be explained by means of the exact production terms in the transport equation for the second-moments of the velocity fluctuations. These changes were in turn consistent with the observed alterations of the mean flow field.
ASJC Scopus subject areas
- Engineering(all)
- Computational Mechanics
- Physics and Astronomy(all)
- Condensed Matter Physics
- Engineering(all)
- Mechanics of Materials
- Engineering(all)
- Mechanical Engineering
- Chemical Engineering(all)
- Fluid Flow and Transfer Processes
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In: Physics of fluids, Vol. 23, No. 7, 075108, 27.07.2011.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Particle image velocimetry measurements of massively separated turbulent flows with rotation
AU - Visscher, Jan
AU - Andersson, Helge I.
N1 - Funding Information: The assistance of Dr. Joël Sommeria and Dr. Henri Didelle (LEGI, Grenoble) and Dr. Mustafa Barri (NTNU, Trondheim) is appreciated. Professor J. P. Johnston (Standford University) kindly sent us the tabulated reattachment-length data included in Figure . The work reported in this publication was supported by the European Community’s Sixth Framework Programme through the grant to the budget of the Integrated Infrastructure Initiative HYDRALAB III, Contract no. 022441 (RII3), and by the Research Council of Norway through a research grant Contract no. 171725/V30.
PY - 2011/7/27
Y1 - 2011/7/27
N2 - Measurements of instantaneous velocity fields in the separated flow downstream of a backward-facing step in a rotating channel are presented for the first time. Particle image velocimetry (PIV) measurements were made for 13 different rotation numbers Ro at a bulk flow Reynolds number of about 5600. The expansion ratio 2:1 was the same as in the flow visualization study by Rothe and Johnston [ASME J. Fluids Eng. 101, 117 (1979)] which covered about the same range of Ro. The measured mean flow pattern exhibited substantial variations with the rate of system rotation. In particular, the length of the primary separation bubble decreased monotonically with increasing anti-cyclonic rotation and increased with increasing rate of cyclonic rotation, in keeping with the earlier observations. At the highest anti-cyclonic rotation rate, the flow field also separated from the planar wall where the shear layer flow was subjected to cyclonic rotation. The PIV data for the in-plane components of the Reynolds stress tensor were severely affected by the imposed system rotation. Almost all the striking affects of the Coriolis force observed herein could be explained by means of the exact production terms in the transport equation for the second-moments of the velocity fluctuations. These changes were in turn consistent with the observed alterations of the mean flow field.
AB - Measurements of instantaneous velocity fields in the separated flow downstream of a backward-facing step in a rotating channel are presented for the first time. Particle image velocimetry (PIV) measurements were made for 13 different rotation numbers Ro at a bulk flow Reynolds number of about 5600. The expansion ratio 2:1 was the same as in the flow visualization study by Rothe and Johnston [ASME J. Fluids Eng. 101, 117 (1979)] which covered about the same range of Ro. The measured mean flow pattern exhibited substantial variations with the rate of system rotation. In particular, the length of the primary separation bubble decreased monotonically with increasing anti-cyclonic rotation and increased with increasing rate of cyclonic rotation, in keeping with the earlier observations. At the highest anti-cyclonic rotation rate, the flow field also separated from the planar wall where the shear layer flow was subjected to cyclonic rotation. The PIV data for the in-plane components of the Reynolds stress tensor were severely affected by the imposed system rotation. Almost all the striking affects of the Coriolis force observed herein could be explained by means of the exact production terms in the transport equation for the second-moments of the velocity fluctuations. These changes were in turn consistent with the observed alterations of the mean flow field.
UR - http://www.scopus.com/inward/record.url?scp=79960929235&partnerID=8YFLogxK
U2 - 10.1063/1.3599702
DO - 10.1063/1.3599702
M3 - Article
AN - SCOPUS:79960929235
VL - 23
JO - Physics of fluids
JF - Physics of fluids
SN - 1070-6631
IS - 7
M1 - 075108
ER -