|Fluid Physics and Transport Phenomena|
Earth’s Gravity creates forces in fluid systems that
induce pressure and flows. In microgravity, the behavior
of fluid systems is driven by other forces not easily
observed on Earth. Design of space systems requires the
understanding of the microgravity behavior of fluids in
pumps, boilers, etc. And this understanding has direct
benefit on Earth where these forces also can be critical
to optimal design.
Everyone has practical experience with fluids -- liquids and gases -- and knows how a fluid will behave under "normal" circumstances. Steam rises from the surface of a boiling pot, and water spilled on a tabletop runs over, then off, the surface. Many of our intuitive expectations do not hold up in microgravity, though, because other forces such as surface tension control fluid behavior.
Surface tension causes drops of any liquid to form almost perfect spheres when the influence of gravity is absent. On Earth, gravity distorts the shape when liquid is resting on or attached to a surface. While these differences in fluid behavior often present engineers and astronauts with practical problems, they also offer scientists unique opportunities to explore different aspects of the physics of fluids.