Model equation calculations of the turbulent flow between rotating cylinders and the structure of a turbulent vortex

Author(s):  
D. D. Knight ◽  
P. G. Saffman
1992 ◽  
Vol 68 (10) ◽  
pp. 1515-1518 ◽  
Author(s):  
Daniel P. Lathrop ◽  
Jay Fineberg ◽  
Harry L. Swinney

It is not possible to distinguish between the Momentum Transport and the Vorticity Transport theories of turbulent flow by measurements of the distribution of velocity in a fluid flowing under pressure through pipes or between parallel planes. Only simultaneous measurements of temperature and velocity distribution are capable of distinguishing between the two theories in these cases. On the other hand, it will be seen later that measurements of the distribution of velocity between concentric rotating cylinders are capable of distinguishing between the two theories; in fact the predictions of the two theories in this case are sharply contrasted and mutually exclusive.


2017 ◽  
Vol 14 (136) ◽  
pp. 20170453 ◽  
Author(s):  
Christian Lindemann ◽  
Andre Visser ◽  
Patrizio Mariani

Turbulence and coherent circulation structures, such as submesoscale and mesoscale eddies, convective plumes and Langmuir cells, play a critical role in shaping phytoplankton spatial distribution and population dynamics. We use a framework of advection–reaction–diffusion equations to investigate the effects of turbulent transport on the phytoplankton population growth and its spatial structure in a vertical two-dimensional vortex flow field. In particular, we focus on how turbulent flow velocities and sinking influence phytoplankton growth and biomass aggregation. Our results indicate that conditions in mixing and growth of phytoplankton can drive different vertical spatial structures in the mixed layer, with the depth of the mixed layer being a critical factor to allow coexistence of populations with different sinking speed. With increasing mixed layer depth, positive growth for sinking phytoplankton can be maintained with increasing turbulent flow velocities, allowing the apparently counter-intuitive persistence of fast sinking phytoplankton populations in highly turbulent and deep mixed layers. These dynamics demonstrate the role of considering advective transport within a turbulent vortex and can help to explain observed phytoplankton biomass during winter in the North Atlantic, where the overturn of deep convection has been suggested to play a critical role in phytoplankton survival.


The stability of fluid contained between concentric rotating cylinders has been investigated and it has been shown that, when only the inner cylinder rotates, the flow becomes unstable when a certain Reynolds number of the flow is exceeded. When the outer cylinder only is rotated, the flow is stable so far as disturbances of the type produced in the former case are concerned, but provided the Reynolds number of the flow exceeds a certain value, turbulence sets in. The object of the present experiments was partly to measure the torque reaction between two cylinders in the two cases in order to find the effect of centrifugal force on the turbulence, and partly to find the critical Reynolds numbers for the transition from stream-line to turbulent flow. The apparatus is shown diagrammatically in fig. 1.


2018 ◽  
Author(s):  
Md. Ibrahim Khalil ◽  
Shoaib Anwar ◽  
Sumon Saha ◽  
Md. Quamrul Islam

1968 ◽  
Vol 90 (1) ◽  
pp. 285-296 ◽  
Author(s):  
J. H. Vohr

The critical speeds for onset of Taylor vortices inflow between eccentric rotating cylinders are determined by means of torque measurements for various eccentricity ratios and clearance ratios of the cylinders. Results are compared with the theoretical and experimental work of other investigators. Visual studies are made of the flow in both the Taylor vortex and turbulent flow regimes. Friction factor data are obtained for Reynolds numbers up to 40,000.


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