Moving liquids without gravity aboard the International Space Station can be tricky -- if there's no "down" then water won’t flow downhill. Capillary Flow Experiments-2, or CFE-2, a physical science investigation looking at fluid physics, is a set of experiments exploring how fluids move up surfaces in microgravity.
Scientists and engineers will use the results of this research to improve computer models used by designers of low-gravity fluid systems, looking for solutions to fluid challenges involving the storage, transport, and processing of liquids in space. Demonstrating liquid separation from gas in microgravity is important for water purification systems needed for space travel. On Earth, CFE results also are being used to improve fluid flow in miniaturized biological devices used for health screening and analysis -- known as "lab-on-a-chip" technology -- along with providing a more fundamental understanding of capillary effects in porous materials and water uptake in soils. This technology is also used for pharmaceutical drug research.
In this interview, Mark Weislogel, CFE-2 Principal Investigator from Portland State University, said, "At certain angles, fluid will wick up certain passageways and change its orientation. By doing that, we can develop the math skills to predict this behavior, so we can design a tank that would exploit the shape to get the liquid to go in one direction." It is all about the math. "In the end, what comes out of our work is an equation, and that can be used to very efficiently and very effectively design systems and improve processes," Weislogel said.