Three-dimensional numerical simulation on the thermocapillary convection in an annular pool of silicone oil heated from inner wall

In order to investigate the characteristics ofthermocapillary flow instability, thermocapillary convection is investigatedwith three-dimensional numerical simulation in a shallow annular pool (depthd =1mm) of silicone oil (0.65cSt, Pr= 6.7) with the heated inner walland the cooled outer wall. The numerical results show that, surface temperaturegradient in the pool heated from inner wall is 10% higher than thatheated from outer wall with a fixed temperature difference between the outerand inner walls. Meanwhile, the critical Marangoni number for the incipienceof hydrothermal wave (Ma_c=3.06\times 10^5) in the pool heated frominner wall is smaller than that (Ma_c=3.34\times 10^5) heated fromouter wall. Furthermore, numerical results indicate the oscillatorymulticellular wave in the pool heated from inner wall when Ma exceedsMa_c. The oscillatory multicellular wave is composed of two hydrothermalwaves propagating in opposite azimuthal directions, which are interferedeach other to be dot ripple.