Nonlinear fluid dynamics research
A levitating droplet is largely deformed by rotation or external forces. However, the relation between external forces and deformation has not been established yet for all cases of deformation (Note: for slight deformation, a proportional relation is effective). Thus, we have to take into consideration complex nonlinearity effects. Fig 5 shows a highly deformed shape of a ca. 2 mm diameter levitating droplet. With such experiments and theoretical study, we are investigating the nonlinear effect on the surface or internal flow. Since the levitation of large droplets is possible in microgravity, we can conduct highly precise experiments. This research is expected to contribute to the development of boundary-surface fluid dynamics, now being increasingly studied, and to improve the accuracy of thermal property measurements mentioned above.
Fig. 5 Observation of a greatly deformed droplet (White part in center of about 2 mm diameter).
Creation of new-function materials by coagulation from extreme supercooling
Since metastable materials often show new functions, we are implementing research aimed at creating new-function materials by coagulation from extreme supercooling. For this research, we developed a technology to levitate melts by ultrasonic or aerodynamic forces. Fig 6 shows the equipment for ultrasonic levitation. Using this equipment, we succeeded to grow oxide superconductive material at process speed of about 100,000 times faster than that in the past. Moreover, we successfully produced a new material that has an extremely high specific inductive capacity of about 100,000. We are now investigating the emerging mechanism of this new function. We also succeeded in producing a spheroid single crystal of ca. 2 mm in diameter by gas levitation. This material is expected to be applicable for spherical lens used in coupling components of optical fiber. Defining the gravity dependency for mechanism investigation of new function emergence by supercooling coagulation on the ground, we intend to perform experiments in microgravity to produce larger samples.
Fig. 6 Ultrasonic levitator
In this article, I have introduced representative research in material sciences performed at JAXA. In addition to these, other research in the field of life, combustion, and basic science are implemented at JAXA.