Numerical simulation of hydro-thermal waves in liquid bridges with variable viscosity Original Research Article

Transition from two-dimensional steady thermoconvective flow to three-dimensional, time-dependent flow is numerically investigated for a liquid bridge with unit aspect ratio Γ = d/R = 1 formed from a medium-Prandtl-number fluid, Pr = 1 – 5. It is assumed that the viscosity of the liquid depends upon temperature. The present calculations demonstrate significant influence of temperature-dependent viscosity on the threshold of instability, i.e., in terms of the critical Reynolds number and frequency of oscillations. For the parametric study of the problem with variable viscosity, the choice of the reference temperature has significant influence on the final result. It is shown that for Pr = 4 instability begins as a traveling wave with azimuthal wave number m = 2 despite the initial disturbances of the system. Contrary to this, for smaller Prandtl number, Pr = 1, the instability begins as a standing wave with the same wave number m = 2.