Miscible Fluids in Microgravity (MFMG): A zero-upmass investigation on the International Space Station

Miscible Fluids in Microgravity (MFMG) was a zero-upmass investigation performed on the International Space Station. The goal of MFMG was to determine if interfacial phenomena seen with immiscible fluids could be seen with miscible fluids. The experiments had to be performed with existing materials on the ISS. Honey and water were chosen as the fluids, and urine collection syringes were used as the vessels in which the experiments were performed. In March 2004 (Increment 8) Dr. Michael Foale performed four experiments under isothermal conditions to determine: If a stream of honey injected into water would exhibit the Rayleigh-Tomotika instability and break into small drops. If an aspherical drop of water in honey would spontaneously assume a spherical shape. The experiments were performed successfully. During Increment 9, Mike Fincke performed two runs in which a stream of honey was injected into water while the syringe was attached to the surface of the Commercial Generic Bioprocessing Apparatus (CGBA) at approximately 31° C. No change in the stream shape was observed. Two more runs were performed on Increments 10 and 11 but no additional phenomena were observed. No behavior beyond simple diffusion was observed. We performed simulations with the Navier-Stokes equations plus a Korteweg stress term. We estimated that the maximum possible value of the square gradient parameter was 10−12 N for the honey-water system.