New Bifurcations in a Partially Filled, Horizontal, Rotating Cylinder

Abstract

One of the main topics in this workshop has been travelling waves in non-equilibrium systems. I describe a new experiment, where both standing and travelling waves can occur as a part of a rich bifurcation structure. The physical system is a very viscous fluid (golden syrup), which partially fills a horizontal cylinder that is rotating around its axis. The length of the cylinder is fixed, 24cm, and the radius R is 4.5cm. In order to show the greatest variety of phenomena the volume fraction of the fluid has been chosen to be 80%. The fluid is at room temperature, and there is no possibility of controlled adjustments. The basic structure of the bifurcations is not sensitive to changes in temperature of even several degrees. However, the details, like the critical speeds and the existence of standing or travelling waves, depend strongly on temperature. This is because the viscosity and other fluid properties are highly sensitive to temperature changes. Without temperature control the present results are only qualitative.