175 research outputs found
Criteria Of Turbulent Transition In Parallel Flows
Based on the energy gradient method, criteria for turbulent transition are
proposed for pressure driven flow and shear driven flow, respectively. For
pressure driven flow, the necessary and sufficient condition for turbulent
transition is the presence of the velocity inflection point in the averaged
flow. For shear driven flow, the necessary and sufficient condition for
turbulent transition is the existence of zero velocity gradient in the averaged
flow profile. It is shown that turbulent transition can be effected via a
singularity of the energy gradient function which may be associated with the
chaotic attractor in dynamic system. The role of disturbance in the transition
is also clarified in causing the energy gradient function to approach the
singularity. Finally, it is interesting that turbulence can be controlled by
modulating the distribution of the energy gradient function.Comment: The Third International Symposium on Physics of Fluids (ISPF3) 15-18
June, 2009, Jiuzhaigou, China. 6 pages; 1 figur
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