Instabilities of thermocapillary flows in large Prandtl number liquid bridges between two coaxial disks with different radii

Abstract

We explore the geometric effects on the thermocapillary flow instabilities in large Prandtl number (Pr=1.4) liquid bridges between two coaxial disks with different radii under microgravity, focusing on the impacts of radius ratio Γr and aspect ratio Γ. The static deformation of the free surface is concerned by the solution of the Young-Laplace equation, and the linear stability analysis based on spectral element method is conducted for accurate identification of the instability characteristic. We observe that the flow stability is generally improved with the decrease of radius ratio Γr or aspect ratio Γ, especially for the liquid bridge heated from the upper disk. The critical oscillation frequency experiences an abrupt drop around Γr=0.56 as Γr decreases for the liquid bridge with the bottom disk heated. Moreover, three transitions between two-dimensional axisymmetric steady flow and three-dimensional oscillatory flow are observed within the interval 0.87<Γ{less than or equal to}0.91 at Γr=0.50 when the liquid bridge is heated from the upper disk. The energy analysis indicates that the instabilities for all cases are predominantly caused by the hydrothermal wave instability and the phenomenon of three transitions results from the variation of thermal energy transfer efficiency with the growth of the Marangoni number.

Particle Swarm Optimization for exploring Darcy–Forchheimer flow of Casson fluid between co-axial rotating disks with the Cattaneo–Christov model

“…Nayak et al 12 focused on the interfacial layer and shape effects of the nanoparticles of CNTs dispersed in water to explore the flow features of electromagnetic Darcy–Forchheimer flow. The study reported that "augmenting the interfacial layer parameter enhances heat transportation from the surfaces of the lower and upper disks.” Flow instabilities under microgravity for fluid flowing between co-axial disk was investigated by Wang et al 13 , Wang et al 14 . Vijay and Sharma 15 used FC-72-based nanofluid to examine the heat and mass transfer features of fluid flowing between co-axial rotating disks subjected to a magnetic field.…”

Variety of flow patterns in a liquid bridge subjected to a gas stream

“…This motivated the development of more complicated numerical models including the static [23][24][25] and dynamic [26,27] interface deformations. Further complication of the model includes either unequal in radius [28,29] or non-flat supporting discs [30] as well as external thermal perturbations [31].…”