Meeting room "Glova", 4 floor, Integrated Research Building
Abstract
We performed a linear stability analysis on the onset of thermal convection of fluid in the presence of spatial variation of physical properties. The viscosity of the fluid is exponentially dependent on temperature, while thermal expansivity and thermal conductivity are linearly dependent on pressure (or depth). The geometry, planar layer model, is employed. The top and bottom boundary conditions are taken to be either free-slip or rigid surface. We seek for critical values of Rayleigh number which characterizes the onset of convection. Velocity field and temperature distribution are also obtained as infinitesimal perturbations for given horizontal wavelength. We examine the influence on convection patterns of the magnitude in spatial variation in physical properties. Our analysis successfully reproduced the transition in flow patterns into the ‘stagnant lid’ regime where a thick and stagnant lid of cold fluid develops at the top surface due to the very strong temperature dependence of viscosity. These flow patterns are quite similar to the one obtained in finite-amplitude convection. Moreover, we found that the presence of spatial variation in thermal expansivity and thermal conductivity changes the convective planform and moderately affects the onset of stagnant lid regime. Increasing the degree of spatial variation of properties other than the viscosity inhibits the development of cold layer on top surface. In the presentation, the details of numerical results and future directions will be discussed.
For inquiry：Taku Tsuchiya TEL:（089）927-8198
E-mail takut@sci.ehime-u.ac.jp
