Flow instabilities in thermocapillary liquid bridges between two coaxial disks with different radii

• Published in: International journal of heat and mass transfer 2022-02, Vol.183, p.122182, Article 122182
• Main Authors: Wang, Yue, Zeng, Zhong, Liu, Hao, Zhang, Liangqi, Yin, Linmao, Xiao, Yao, Liu, Yong
• Format: Article
• Language: English
• Subjects: Disks; Energy budget; Flow instability; Flow stability; Free surfaces; Heating; Instability mechanism; Laplace equation; Liquid bridges; Microgravity; Prandtl number; Spectral element method; Stability analysis; Static deformation; Thermocapillary flow
• ISSN: 0017-9310; 1879-2189
• DOI: 10.1016/j.ijheatmasstransfer.2021.122182

•The oscillatory bifurcation in liquid bridges with unequal disks is reported.•The critical mac can be 7–10 times improved with the decrease of radius ratio Γr.•The critical stability curves for Pr=0.011 under microgravity are presented.•Perturbation energy analysis is performed to reveal the instability mechanisms.•The instabilities are found to be purely hydrodynamic. The primary instability of thermocapillary flow in a liquid bridge between two coaxial disks with different radii is investigated under microgravity for silicon melt with Prandtl number Pr=0.011 via two heating strategies. The static deformation of the free surface is considered by solving the Young-Laplace equation. The physical instability mechanisms are explored by analyzing the energy budgets of the critical modes, which are determined by linear stability analysis based on the Legendre spectral element method. With the decrease of radius ratio Γr, the stability of thermocapillary flow is significantly improved. In contrast to typical cylindrical liquid bridges (Γr=1), the instability is an oscillatory bifurcation for small radius ratios (Γr≤0.672) when the liquid bridge is heated from the bottom disk. Furthermore, the instabilities for all radius ratios and heating strategies are found to be purely hydrodynamic, but the specific instability mechanisms are different.