Origin of Axially Running Waves in Liquid Bridges

A supercritical three-dimensional thermoconvective flow in a long non-isothermal liquid bridge with aspect ratio Γ?=?1.8 is numerically investigated under terrestrial conditions. Study of the flow regimes shows that the instability sets in as an axially running wave with zero wave number, m?=?0, which is a two-dimensional unsteady flow. Further increasing the applied temperature difference results in bifurcation of m?=?1 wave traveling azimuthally with a slightly higher frequency. The two waves co-exist within a certain range of the temperature difference values, and finally the m?=?0 wave is suppressed while the azimuthal one gets stronger.