May the capillary force be with you

Future astronauts may boldly go farther than ever before, thanks to research at Washington State University recently funded by NASA to study fluids in space.

Liquids are used in many space station systems, such as fueling, heating and cooling. Oxygen for breathing is also stored as a liquid. As space missions get longer, researchers want to conserve energy when moving these fluids in order to make longer space missions possible.

Led by Sinisa Mesarovic, professor in the WSU School of Mechanical and Materials Engineering, the researchers will study capillary forces for moving liquids through narrow spaces. The goal is to develop a computer model and designs for improved liquid transport systems for future spacecraft.

Capillary forces move liquid via materials that either attract or repel it. For example, when a straw is put into a glass of water, the water level inside the straw is higher than the level in the glass.

"This is because the straw is made of material that likes contact with water," Mesarovic said. "Capillary forces can hold a certain weight of water above the water lever in the glass."

On Earth, capillary forces have to fight gravity. But in space, the only resistance is the viscosity of the liquid, which slows the flow but cannot stop it.

Mesarovic's team will use the experiments conducted aboard the International Space Station during the past few years to quantify capillary flow in the absence of gravity. The researchers will develop a predictive computational model and, eventually, designs for better liquid transport systems.

Provided by Washington State University