Non-reversing modulated Taylor-Couette flows

We study the stability of Couette flow in the case in which the outer cylinder is held fixed and the speed of the inner cylinder oscillates harmonically with time around zero mean. We find that, if the amplitude of the oscillation is large enough, it is possible that the resulting time-dependent Taylor vortex flow rotates in a direction which does not depend on the direction of the azimuthal motion which drives it. The transition to this “non-reversing” Taylor vortex flow is examined as a function of frequency of modulation and radius ratio. We also find that “non-reversing” flow is present in the wavy modes regime.