use of the piv and electrochemical techniques to experimentally characterize the couette-taylor-poiseuille flow instabilities

The taylor-couette problem is a fundamental model in bifurcation theory and hydrodynamic stability. the inner cylinder rotation generates a flow pattern known by a transition to turbulence through a sequence of successive hydrodynamic instabilities. the effect of an imposed axial flow on the instabilities evolution is studied. an experimental device was designed to study this effect. it consists of two concentric cylinders with the inner one rotating and the outer one fixed, and a pressure driven axial flow can be superimposed in the annulus. in addition, various motion of the inner cylinder can also be imposed (oscillation, gradual or abrupt disturbance).the objectives are to investigate the effect of the superposition of an axial flow on the stability of the flow and its influence on the vortex behavior and hence on the wall shear stress. the resulting structure of the flow then depends on the initial flow regime, due to the rotation of the inner cylinder and the velocity of the axial flow. consequently, two dimensionless parameters are defined to characterize the flows: the taylor number and the reynolds number of the axial flow. experimental piv measurements are devoted to characterize the taylor-couette flow dynamics with imposed axial flow and then synchronized with electrochemical measurements to study the vortex-wall interaction.