A team of students from the University of Florida, led by Prof. Narayanan Ranga, has developed an experiment called ‘Gator GrAvitational effecTS on the faraday instaBilitY’ (Gator GATSBY) with the purpose of investigating pattern formation at the interface of two liquids, when resonance is forced on a stacked layer of fluids in conditions of microgravity.
‘Gator GrAvitational effecTS on the faraday instaBilitY’ (Gator GATSBY) project aims to study the Faraday instability in reduced gravity, to compare it with ground-based experiments and theory.
The effects of the Faraday instability in the disappearance of capillary and gravitational effects remains theoretically and experimentally unexplored. Hence, the project also looks into the determination of the nature of this instability.
Gator GATSBY was developed by the University of Florida in collaboration with ICE Cubes (Space Applications Services), under a grant from National Science Foundation and ISS National Lab. Set for launch in early November 2022, the cube will spend 6 months on board the International Space Station, hosted inside the ICE Cubes Facility.
The results of this investigation may lead to improved techniques in substrate patterning, pulsatile fluid sensors, and heat transfer in micro-geometries for applications such as thermal management and bubble transport in space, but also on Earth with applications such as jetting processes, bubble removal for cleaning surfaces, and microscale heat transfer.
An interface is a thin region between two adjacent bulk fluids. Resonant interfacial instability is characterized by waves at the interface between liquid bilayers. Physically, a wave pattern appears on the surface of a liquid when the imposed frequency resonates with the natural frequency of the system. Standing waves occur at interfaces when one or more liquids vibrate perpendicular to the liquid surface or liquid interface. This phenomenon is known as Faraday instability and results from the application of cyclic forces consistent with the fluid system.
The effect of interfacial tension on the waves is enhanced by the reduction of gravity and open up to study different characteristics of Faraday instability. Hence, the reasoning behind conducting this research in space. Moreover, it is hypothesized that the critical nature of the instability depends on the forcing frequencies, when gravity is reduced.
For this investigation, resonance is achieved at the interface of a liquid bilayer. While the threshold conditions for instability under Earth’s gravity are unaffected by the interfacial tension value, microgravity may can help to isolate the interfacial tension. For that, Gator GATSBY is contained in a cube with four cuvettes with various fluids. The oscillation is conducted at different amplitudes and frequencies while high-speed cameras acquire videos of the phenomenon. The results generated can be analysed in the same day via the real-time capabilities of the service.