Linear-stability analysis of thermocapillary-buoyancy convection in annular two-layer system with a radial temperature gradient

Author(s):  
Xi-Wu Gong ◽  
Dong-Ming Mo ◽  
Chun-Mei Wu ◽  
You-Rong Li
1998 ◽  
Vol 359 ◽  
pp. 143-164 ◽  
Author(s):  
R. J. RILEY ◽  
G. P. NEITZEL

Combined thermocapillary–buoyancy convection in a thin rectangular geometry is investigated experimentally, with an emphasis on the generation of hydrothermal-wave instabilities. For sufficiently thin layers, pure hydrothermal waves are observed, and are found to be oblique as predicted by a previous linear-stability analysis (Smith & Davis 1983). For thicker layers, both a steady multicell state and an oscillatory state are found to exist, but the latter is not in the form of a pure hydrothermal wave.


2019 ◽  
Vol 879 ◽  
pp. 422-447 ◽  
Author(s):  
Sicheng Zhao ◽  
Mathias Dietzel ◽  
Steffen Hardt

The Faraday instability in a system of two conjugated immiscible liquid layers with disparate thicknesses is investigated. The top layer is relatively thick and undergoes short-wavelength instabilities, while the bottom layer is thin and undergoes long-wavelength instabilities. The two layers are coupled by the kinematic and dynamic relations at the interface. Through linear stability analysis, a lubrication effect, which significantly reduces the destabilization threshold, is identified. Especially when the vibration frequency is low, the lubrication effect is seen to influence the transition between the harmonic and subharmonic instability modes. It is studied how far the system with two layers can be approximated by a single-layer system with a Navier-slip boundary condition at the bottom. In corresponding experiments it is found that the time-periodic excitation of the system creates a steady-state deformation of the bottom layer. This indicates nonlinear dynamics of the system and the violation of reversibility. The excellent agreement between experimental and theoretical results for the onset of the instability underpins the validity of the linear stability analysis.


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