Mixing and Separation of Transparent Liquids Under Microgravity Conditions.

This paper reports on the development of a model experiment on the mixing and separation of metallic alloys and gives the results. The experiment was flown in the German spacelab mission D1. A liquid column of 35 mm in diameter and height was produced from a pair of liquids which mix and separate at temperatures above and below 47 degree C, respectively. During the heating of the column to 60 degree C, Marangoni convection along the surface, bubble migration and extrusion, the spreading of one component along the heated disk, the breaking of the inner liquid column into two spherical segments and a gradual dissolution of the interface between the two components were observed. During the subsequent cooling of the column by heat radiation and conduction, fog was formed due to separation and the fog migration regions were formed due to Marangoni convection. At 75 degree C the two liquids did not assume an axisymmetric configuration.