Instabilities of Flow State in Taylor-Couette Geometries

Investigations of Taylor-Couette flow have been carried out under quasistatic changes of the Reynolds number to study the flow development in the lower Reynolds number regime. The object of the first series of investigations is to determine the stability boundary of Taylor Vortex Flow as a function of the Reynolds number and radius ratio. Four different types of transitions from Taylor Vortex Flow to Wavy Vortex Flow are observed. The measured stability boundary agrees with the calculated one remarkably well. The second series of investigations are focused on higher transitions of the Wavy Vortex Flow in one specific radius ratio. A new analytical technique is used to study: (1) a vortex pair annihilation and creation in an m = 2 Wavy Vortex Flow, (2) an m = 2 to an m = 3 wavy mode transition, and (3) an oscillatory behavior in an m = 3 Wavy Vortex Flow. The present work shows that the width of the indeterminate region between two adjacent m-mode states arises from non -quasistatic ramping. Under sufficiently slow ramping, the m-mode transitions are sharp. When the Reynolds number is increased quasistatically across the first m-mode transition, non-uniform vortex size distribution is attained. This non-uniformity travels in the axial direction in an oscillatory manner. This behavior depends strongly on the aspect ratio and the Reynolds number.