Capillary flow along rounded interior corner of right-angle under microgravity

It is crucial to investigate the capillary driven flows along interior corners because of the interior corners of space fluid management devices provide the main conduits for the transfer of fluids. In many instances, the interior corners are not perfectly sharp but rather possess a degree of roundedness due to the design or fabrication. In this work, the problem of capillary flows along rounded interior corners is revisited experimentally. Four test cells which are made of PMMA are designed. The cross sections of the four cells are the same pentagon except that one 900 corners are rounded with different radius R0 (sharp corner), R2.4, R4.8, R6, respectively. Four kinds of liquids are used in the microgravity drop tower tests, i.e. KF96-5 silicone oil, KF96-10, KF96-50 and Fluorinert liquid FC-70. The experimental results show that the advancing meniscus tip location of the fluid in the corner L (mm) is affected by container geometry and fluid properties. These experimental results are valuable to better understand the capillary flow and also can provide scientific guidance for the design and analysis of space fluid management systems. © 2009 SPIE

Oscillatory flow at the onset of convection in two-layer Bénard-Marangoni system

In this paper, the time-dependent Be´nard-Marangoni convections of two-layer fluid at the onset of convection are investigated experimentally. The flows are visualized from side with particle image velocimetry (PIV) and structure change of velocity fields near onset of convection are observed while the depth ratio varies in a range. The variation of the critical temperature difference with the depth ratio shows that the "peak depth ratio" is very far from the "balancing depth ratio"; the oscillatory onsets from stationary were obtained in a big gap of depth ratio in which the "peak depth ratio" located. These results don't agree with the predications of the linear stability analysis