Capillary Flow Experiment

The Capillary Flow Experiments are a suite of fluid physics flight experiments designed to investigate large-length-scale capillary flows and phenomena in low gravity. The experiments studied phenomena that could not be studied on the ground, such as dynamic effects associated with a moving contact boundary condition, capillary-driven flows in interior corner networks, and critical wetting phenomena in complex geometries.

The CFE-2 hardware consists of a suite of 11 manually operated test vessels that vary in geometry. The test vessels for the original experiments contained silicone oil that varied in viscosity ranging from 2 cSt to 20 cSt. The volume of silicone oil contained by each vessel also varied from approximately 21 cc to 54 cc. Each unit consists of an acrylic vessel containing both a fluid reservoir (for fluid storage during launch and stowage) and a test chamber with a unique capillary geometry of interest to the researcher. For test operations, the fluid is pumped in between the reservoir and test chamber via a piston, manually rotated by a crew member, and controlled via manually manipulated valves. Modification of the test liquid and fluid volume is possible. In addition, it is also possible to design and build new units with a similar configuration (i.e., a test chamber and fluid reservoir) to explore capillary forces in complex containers. The experiments are carried out on the Maintenance Work Area (MWA) on the ISSInternational Space Station, and the science data is recorded using a high-definition camera.