Simulated microgravity in the ring-sheared drop

Abstract

The ring-sheared drop is a module for the International Space Station to study sheared fluid interfaces and their influence on amyloid fibril formation. A 2.54-cm diameter drop is constrained by a stationary sharp-edged ring at some latitude and sheared by the rotation of another ring in the other hemisphere. Shearing motion is conveyed primarily by the action of surface shear viscosity. Here, we simulate microgravity in the laboratory using a density-matched liquid surrounding the drop. Upon shearing, the drop’s deformation away from spherical is found to be a result of viscous and inertial forces balanced against the capillary force. We also present evidence that the deformation increases with increasing surface shear viscosity.

Coupling Vortical Bulk Flows to the Air–Water Interface: From Putting Oil on Troubled Waters to Surfactants on Protein Solutions

“…The resultant bulk flow is practically indistinguishable from the case where a rigid solid lid is placed at the free surface immediately after the columnar vortex is generated [51]. Recently, a containerless biochemical reactor was introduced for the microgravity environment where containment is achieved by surface tension and shear is propagated primarily by the action of the surface shear viscosity [52][53][54][55]. Such a ring-sheared drop, shown schematically in Figure 2a, is driven by the rotation of a thin contact ring at some latitude in the top hemisphere along with a stationary ring in the bottom hemisphere.…”

Single-camera PTV within interfacially sheared drops in microgravity

“…1). (Gulati et al, 2017(Gulati et al, , 2019(Gulati et al, , 2018McMackin et al, , 2020Riley et al, 2021) The original investigation (2019 and 2021 ISS flight campaigns) of the RSD focused on the effects of interfacial shear on the fibrillization kinetics (amyloidogenesis) of human insulin, centering on flow's effect on the biological system. However, changes in the biological system also produce reciprocal changes in fluid flow.…”