Subcritical Transition and Spiral Turbulence in Taylor-Couette Flow

We present measurements characterizing the transition to turbulence in Taylor-Couette flow for~a fully cyclonic regime, i.e. with only the outer cylinder rotating. Under this arrangement the flow is linearly-stable and the shear-driven transition to turbulence is understood to be~both `catastrophic' and spatiotemporally intermittent. En route to a fully turbulent state, we observe a regime featuring co-extant laminar/turbulent domains known as spiral turbulence. To better understand this regime, and the transition in general, we have obtained~velocimetry data (via LDV) and~angular momentum transport estimates (via torque), in~addition to flow visualization. These observations are discussed with respect to~similar transition phenomena~in planar and counter-rotating Couette flows. By utilizing three different inner cylinder radii within the apparatus, we also demonstrate the sensitivity of the subcritical transition scenario to annular~gap width.