Single streamwise vortical structure and its instability in shear flows
Thesis/Dissertation
·
OSTI ID:6688194
A single streamwise vortex structure is generated from the tip of an obstacle in a shear flow on a water table. Its streamwise velocity field is measured using a laser Doppler velocimetry system with small scattering volume. The strength of the vortex, the vortex Reynolds number, is estimated using Pearson and Abernathy's flow model. An improved flow model with a parabolic velocity distribution as a basic flow field is discussed. The vortex structure in shearing flows is considered as a fundamental flow structure for laminar-turbulent transition. Experiments on natural transition in subcritical flows show that instability of the flow depends on the vortex Reynolds number. By increasing the vortex strength, laminar-turbulent transition occurs at a fixed vortex Reynolds number, independent of the value of the conventional flow Reynolds number. In this manner, transition could always be induced at subcritical flow Reynolds numbers.
- Research Organization:
- Harvard Univ., Cambridge, MA (USA)
- OSTI ID:
- 6688194
- Country of Publication:
- United States
- Language:
- English
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