Visualization study of Taylor-Couette flow: A description of the transition to turbulence

A visualization study wm performed of the Taylor-Couette flow with a medium-gap (η= 0.356), over a large range of Taylor numbers (0.21×10⁵< Ta < 6.81×10¹⁰). Two techniques were used the PHANTOMM technique, where photo-activated dyes ewe used to write lines in the flow, and a particle technique, where a light sheet from an cw ion laser beam illuminated the flow seeded with neutrally buoyant polystyrene microspheres. Our study examined the interplay between small and large scales present in the flow and showed the gradual transition to turbulence with increasing Taylor number s. The Taylor cells were found for Taylor numbers less than 1. 13 × 10¹⁰. At low Taylor numbers, the flow in the cells appeared io be rotational laminar flow with a hgh degree o f coherence. At higher Taylor numbers, the aspect of the cells became more irregular, and the flow inside the cells became turbulent. The Gortler instability developed inside the Taylor cells, close to the inner cylinder wall. At the highest Taylor numbers, the turbulence increased to the po2int where no Taylor cells could be detected For our flow, at Ta = 1.13 × 10¹⁰, the homogenization by turbulence spread across the gap, and the flow structure sharply changed its pattern as a toroidal vortex in helical motion developed in a thin layer on the inner cylinder wall.