The thermally-driven rotating annulus: horizontal velocities in regular and weakly chaotic flow regimes

This dataset contains 11 1/2 hours of horizontal velocity measurements from four experiments using AOPP's 'small annulus' thermally-driven rotating annulus laboratory experiment.

Click $\rightarrow$ here $\leftarrow$ to access the dataset via ORA-Data.

Schematic of the rotating annulus experiment used in this dataset.

The experiments cover regular (2S, 3AV) and weakly chaotic (3SV) flow regimes. The apparatus consists of two concentric right circular cylinders with height 14.0cm and radii 2.5cm and 8.0cm, with a 17% glycerol / 83% water mixture (by volume) between them. The outer cylinder is heated and the inner cylinder cooled relative to the working fluid, with a temperature difference of approximately 4K, and the apparatus rotates about the co-incident axis of the two cylinders at rates between 0.75 and 3.1 rad/s. This setup mimics the main effects acting on a planetary atmosphere: gravity, rotation, and a heating gradient between low and high latitudes.

The method for taking observations is Particle Image Velocimetry. A horizontal plane of light 3 mm thick is shone into the tank at a single vertical level, which reflects off neutrally buoyant particles into a video camera 1 m directly above the fluid, rotating in the same coordinate frame and about the same vertical axis. The particles (500-1000 per frame) are tracked over one second, producing a set of images from which particle positions and velocities are calculated.

Up to five vertical levels are available, depending on the particular datafile, at 12.4, 9.7, 7.0, 4.3 and 1.6cm above the bottom of the tank. Only one vertical level is available at any particular time; the observations cycle through the available levels moving down every 5s.

The position error in each vector is about 0.0040 cm (in each direction), and the error in each velocity component is about 0.0057 cm/s.

The dataset is held by ORA-Data and is licensed under ODC-By v1.0. Note that while the files at that link are listed as .tgz, they are not actually compressed (treat them as .tar files).

Velocity fields at the uppermost observation level (12.4cm)


1.000 rad/s0.975 rad/s0.950 rad/s0.925 rad/s0.900 rad/s0.875 rad/s0.850 rad/s0.825 rad/s0.800 rad/s0.775 rad/s0.750 rad/s


0.875 rad/s0.850 rad/s0.825 rad/s0.800 rad/s0.775 rad/s0.750 rad/s


2.2 rad/s2.3 rad/s2.4 rad/s2.5 rad/s2.6 rad/s


2.6 rad/s2.7 rad/s2.8 rad/s2.9 rad/s3.0 rad/s3.1 rad/s


Please cite the dataset as

Young, R.M.B., Read, P.L., Früh, W.-G., Smith, D. & Risch, S. (2015) The thermally-driven rotating annulus: horizontal velocities in regular and weakly chaotic flow regimes [data-set]. Oxford: Oxford University Research Archive [distributor] $<$DOI 10.5287/bodleian:dr26xx49n$>$.


Roland M. B. Young roland.young [at] University of Oxford (UK)
Peter L. Read [at] University of Oxford (UK)