CENTRIFUGAL INSTABILITY OF PULSED FLOW

The stability of a pulsed flow in a Taylor-Couette geometry with both cylinders rotating at the same angular velocity Omega(t)=Omega(o) cos (omega t) is investigated. The first experimental evidence showing tha t the flow is less unstable in the limit of low and high frequency whi le destabilization is maximum for an intermediate frequency omega(o) i s reported. A detailed analysis of the restabilization at frequencies just above omega(o) reveals a behavior not accounted for by previous t heoretical analysis. Thus, the linear stability analysis is reconsider ed by using a different implementation of the Floquet theory and a sat isfactory agreement with the present experimental results is found.