Layer Formation in Stratified Taylor–Couette Flow

A new set of high Reynolds number experiments (Re = riΩi∆r ν ∼ 10 − 10) are conducted to examine the layer formation observed in stratified Taylor–Couette flow. A wider range of radius ratios η = ri ro (where ri and ro are the radii of the inner and outer cylinder, respectively) than previously possible is explored to examine the universality of the dependence of layer height l on U N , where U is a characteristic velocity scale and N is the buoyancy frequency. Previous work by Oglethorpe et al. (2013) found a linear relationship between l and U N taking a horizontal velocity scale Uh = √ ri∆rΩi, where ∆r = ro − ri is the gap width and Ωi is the rotation rate of the inner cylinder, and this choice of velocity scale is tested with our new, more comprehensive data set. The sensitivity of this scaling to initial conditions is also considered with the use of different spin up protocols, i.e. initiating the experiment in different ways. The different protocols include linearly increasing Ωi with time to some final value, as well as initiating the experiment with a slow spin up, slow compared to viscous diffusion, to solid body rotation before impulsively stopping the outer cylinder.