In the production of high-tech crystals, metals, alloys, and ceramics, materials are heated until they form a liquid or vaporize into a gas and then are cooled until they solidify. During this process, unwanted flows in the liquids and gases, created as the material heats and cools, often cause defects that can keep these materials from performing as predicted or designed. Advanced products, such as the crystals used to make computer chips and infrared detectors, require material that is as free from defects as possible. Temperature variations along the surfaces that are not in contact with a container, called free surfaces, create fluid motions called thermocapillary flows.
Gravity also causes flat surfaces to form on liquids.
In microgravity, investigators can study the different surface shapes that occur and how these shapes affect the thermocapillary flows. The hardware performed flawlessly, with all systems performing as designed. Also, CWRU graduate students monitored the experiment at Lewis and provided additional feedback to the team at the Payload Operations Control Center. The preliminary data supported the CWRU thermocapillary flow theories, which predict the importance of a second critical parameter. The transition to oscillatory flow occurred at a much lower point in low gravity and could be observed in the 3-cm test cell.