Bok-Cheol Sim

TL;DR: In this paper, the authors report results from microgravity experiments on thermocapillary convection in open annuli with outer radius Ro :40 mm and inner radius Ri : 20 mm of various aspect ratios Ar. The measurements are from more than 230 equilibrated states in the Ar Marangoni-number space.

TL;DR: Oscillatory thermocapillary convection in open cylindrical annuli heated from the outer wall was investigated numerically in this paper, with a fixed inner/outer radius ratio of 0.5.

TL;DR: In this paper, the Young-Laplace equation was used to investigate thermocapillary convection driven by uniform heat flux in an open cylindrical container of unit aspect ratio.

Abstract: Oscillatory thermocapillary convection in open cylindrical annuli heated from the inside wall is investigated numerically. Results for aspect ratio of 1 and Prandtl number of 30 are obtained to compare the simulations with available experiments. The influence of space craft or orbital rotation on the critical Reynolds number and pattern of convection through the Coriolis force, as measured by a vector Taylor number of magnitude Ta, is investigated. The flow is steady and axisymmetric at sufficiently low values of Re. In the absence of rotation, we observe a twolobed, isotherm pattern travelling clockwise at the free surface near Recr. Thus the frequency of temperature oscillations is twice that of the isotherm rotation. At supercritical jRe, a two-lobed pulsating isotherm pattern is observed instead. Isotherm patterns on the free surface are in good agreement with experimental results. With Ta less than 1, which is relevant to space applications, the effect of rotation on Recr and flow field is small. Recr is found to decrease with increasing Ta. When the rotation vector is orthogonal to the cylinder axis, the isotherms take a three-lobed pulsating pattern. When the rotation vector is parallel to the cylinder axis, a two-lobed rotating isotherm pattern is observed. It is found that rotation has a stronger influence on the flow field when parallel to the cylinder axis.