Notes and experiments on the statics of capillary columns

Abstract

Experimental results are summarized, concerned with the statics of liquid columns in capillary tubes under non-standard conditions. Three configurations are considered: 1. inclined capillary tubes; 2. capillary effect in the horizontal branch of an L-shaped tube; 3. capillary columns in a vertical tube. The effect of inclination on capillary rise (1.) had already been explored in [1] using water in glass-tubes, and it was found that the vertical rise progressively reduces for increasing the tube inclination. This behaviour is now confirmed for n-Hexadecane (C16H34). For L-shaped capillaries (2.), the length of the horizontal branch of the tube occupied by the liquid is detected, as a function of the elevation of the branch itself over the feeding pool. The statics of suspended liquid columns (3.) is investigated for two configurations, namely: i. freely suspended columns, and, ii. edge-ending columns. In the latter case the evaporation transient is also tracked. Even if the experimental basis is limited, the results are sufficient to highlight some of the peculiar features of the statics of capillary columns under the above conditions. In particular, it is shown that the contact angle hysteresis plays a fundamental role in all the cases considered.