Natural convection induced by unintended horizontal temperature distribution in a narrow-closed container heated from above

This study aims at expressing the velocity fields of the liquids held in a narrow-closed container heated from above as a function of the dimensions of the container to estimate the diffusion-dominant condition. The motions of tracer particles in liquid salol held in a quasi-two-dimensional glass cell were tracked in cavities of various inner width W through the series of experiments. The mean velocity of the tracer particles, V_mean, decreased almost linearly with the decrease in the values of W. Thermal flow fields were successfully reproduced by the series of numerical simulations. We found that the unintended horizontal temperature difference is realized, which induces the natural convection in the closed narrow cavity heated from above. We derived the correlation between the Reynolds and Grashof numbers, which are described as a function of the mean velocity and the unintended horizontal temperature difference, respectively. The threshold of the convection onset in the present geometry was then proposed.