Transition and Modal Structure of Oscillatory Marangoni Convection in Liquid Bridge.

Abstract

河村 洋,小野 嘉久,上野 一郎 Transition and Modal Structure of Oscillatory Marangoni Convection in Liquid Bridge Hiroshi KAWAMURA, Yoshihisa ONO and Ichiro UENO Dept. Mech. Eng., Fac. Sci. & Tech., Science University of Tokyo, 2641 Yamazaki, Noda-shi, Chiba 278-8510, Japan A large number of terrestrial experiments have been conducted on Marangoni convection in a liquid bridge to date. The limitation in the terrestrial experiments lies in the maximum size of the bridge and thus in the maximum attainable Marangoni number in normal gravity. In the present study, a series of experiments was performed in a low temperature environment in order to suppress the evaporation of fluid while realizing a large temperature difference between the both ends of the bridge to attain a high Marangoni number in spite of a small size of the bridge. The test fluid was silicone oil of 1, 2 and 5 cSt. The temperature difference ∆T was increased gradually and a critical point of transition from steady to oscillatory flow was obtained. With increase of ∆T, a pulsative oscillatory mode and then a rotational one became discernable. In this series of experiments a wide range of aspect ratio of the bridge was concerned and thus flow structures with mode number m = 1, 4, 5 and 6 were realized. The product of the mode number and the aspect ratio was found to be approximately unity as often pointed out.