Turbulent bursts and torque maxima in Taylor-Couette flow: Extended abstract

In Taylor-Couette flow with sufficiently strong counter-rotating cylinders, the turbulence near the outer cylinder shows intermittent oscillations in form of turbulent bursts. We present this phenomenon in direct numerical simulations for radius ratios η = 0.5 and 0.71 and identify a critical value in the rotation ratio µ for its onset. We propose a physical model for this critical value that also rationalizes the observed agreement with the rotation ratio of the torque maximum. While this model conforms well with the observations for these radius ratios, it most likely has to be refined or replaced for η → 1, as further simulations for η ≥ 0.9 show.