TY - JOUR
T1 - Energy injection in closed turbulent flows
T2 - Stirring through boundary layers versus inertial stirring
AU - Cadot, O.
AU - Couder, Y.
AU - Daerr, A.
AU - Douady, S.
AU - Tsinober, A.
PY - 1997
Y1 - 1997
N2 - The mean rates of energy injection and energy dissipation in steady regimes of turbulence are measured in two types of flow confined in closed cells. The first flow is generated by counterrotating stirrers and the second is a Couette-Taylor flow. In these two experiments the solid surfaces that set the fluid into motion are at first smooth, so that everywhere the velocity of the stirrers is locally parallel to its surface. In all such cases the mean rate of energy dissipation does not satisfy the scaling expected from Kolmogorov theory. When blades perpendicular to the motion are added to the stirring surfaces the Kolmogorov scaling is observed in all the large range of Reynolds numbers [Formula Presented] investigated. However, with either smooth or rough stirring the measurements of the pressure fluctuations exhibit no Reynolds number dependence. This demonstrates that, though the smooth stirrers are less efficient in setting the fluid into motion, their efficiency is independent of the Reynolds number so that the Kolmogorov scaling characterizes, in all cases, the dissipation in the bulk of the fluid. The difference in the global behaviors corresponds to a different balance between the role of the different regions of the flow. With smooth stirrers the dissipation in the bulk is weaker than the Reynolds-number-dependent dissipation in the boundary layers. With rough (or inertial) stirrers the dissipation in the bulk dominates, hence the Kolmogorovian global behavior.
AB - The mean rates of energy injection and energy dissipation in steady regimes of turbulence are measured in two types of flow confined in closed cells. The first flow is generated by counterrotating stirrers and the second is a Couette-Taylor flow. In these two experiments the solid surfaces that set the fluid into motion are at first smooth, so that everywhere the velocity of the stirrers is locally parallel to its surface. In all such cases the mean rate of energy dissipation does not satisfy the scaling expected from Kolmogorov theory. When blades perpendicular to the motion are added to the stirring surfaces the Kolmogorov scaling is observed in all the large range of Reynolds numbers [Formula Presented] investigated. However, with either smooth or rough stirring the measurements of the pressure fluctuations exhibit no Reynolds number dependence. This demonstrates that, though the smooth stirrers are less efficient in setting the fluid into motion, their efficiency is independent of the Reynolds number so that the Kolmogorov scaling characterizes, in all cases, the dissipation in the bulk of the fluid. The difference in the global behaviors corresponds to a different balance between the role of the different regions of the flow. With smooth stirrers the dissipation in the bulk is weaker than the Reynolds-number-dependent dissipation in the boundary layers. With rough (or inertial) stirrers the dissipation in the bulk dominates, hence the Kolmogorovian global behavior.
UR - http://www.scopus.com/inward/record.url?scp=0031191486&partnerID=8YFLogxK
U2 - 10.1103/PhysRevE.56.427
DO - 10.1103/PhysRevE.56.427
M3 - ???researchoutput.researchoutputtypes.contributiontojournal.article???
AN - SCOPUS:0031191486
SN - 1063-651X
VL - 56
SP - 427
EP - 433
JO - Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics
JF - Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics
IS - 1
ER -