“…Note that the maximum speed for the present oil–water system experiments, obtained with the low viscosity oil, is an order of magnitude larger than the anticipated maximum operating speed of the RSD module on the ISS, estimated to be . 9 However, it should be noted that deformation in a rotating drop is expected to be a function of density difference between the drop and the surrounding fluid. 17,18 Figure 3 also shows that at faster speeds, the drop widens near the rotating ring and narrows near the stationary ring.…”
Section: Resultsmentioning
confidence: 53%
“…These distortions are not left-right symmetric, and videos of the flow are suggestive of the presence of a helical wave mode. If only inertial effects were important, one might expect the drop to spin as a solid-body at as suggested by Gulati et al 9 and bulge out at the equator. However, as we will show below, viscous effects appear to play a significant role here.Fig.…”
Section: Resultsmentioning
confidence: 86%
“…Computations with spherical drops have shown that flow in the azimuthal plane (secondary flow) increases significantly in the presence of surface shear viscosity and the observed drop shape is consistent with the secondary motion induced by surface shear viscosity. 9 In other words, we believe that an additional dimensionless group, namely Boussinesq number , also governs the drop deformation. A large drives a strong meridional flow, 9 which we believe increases the overall drop deformation.…”
Section: Resultsmentioning
confidence: 93%
“…In the presence of macromolecules, such as proteins or microorganisms and their byproducts, the air-water interface exhibits sufficient surface shear viscosity to enable strong bulk flow in drops at scales of up to several centimeters. 9 Fig. 1Overview of hardware.( a ) Schematic of the Ring-Sheared Drop (RSD) hardware onboard the ISS, built by Teledyne–Brown Engr.…”
Section: Introductionmentioning
confidence: 99%
“…More recently, this restriction was removed by considering a large range in , and the coupled flow in the RSD was studied numerically with arbitrarily small surface shear viscosity. 9…”
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.
“…Note that the maximum speed for the present oil–water system experiments, obtained with the low viscosity oil, is an order of magnitude larger than the anticipated maximum operating speed of the RSD module on the ISS, estimated to be . 9 However, it should be noted that deformation in a rotating drop is expected to be a function of density difference between the drop and the surrounding fluid. 17,18 Figure 3 also shows that at faster speeds, the drop widens near the rotating ring and narrows near the stationary ring.…”
Section: Resultsmentioning
confidence: 53%
“…These distortions are not left-right symmetric, and videos of the flow are suggestive of the presence of a helical wave mode. If only inertial effects were important, one might expect the drop to spin as a solid-body at as suggested by Gulati et al 9 and bulge out at the equator. However, as we will show below, viscous effects appear to play a significant role here.Fig.…”
Section: Resultsmentioning
confidence: 86%
“…Computations with spherical drops have shown that flow in the azimuthal plane (secondary flow) increases significantly in the presence of surface shear viscosity and the observed drop shape is consistent with the secondary motion induced by surface shear viscosity. 9 In other words, we believe that an additional dimensionless group, namely Boussinesq number , also governs the drop deformation. A large drives a strong meridional flow, 9 which we believe increases the overall drop deformation.…”
Section: Resultsmentioning
confidence: 93%
“…In the presence of macromolecules, such as proteins or microorganisms and their byproducts, the air-water interface exhibits sufficient surface shear viscosity to enable strong bulk flow in drops at scales of up to several centimeters. 9 Fig. 1Overview of hardware.( a ) Schematic of the Ring-Sheared Drop (RSD) hardware onboard the ISS, built by Teledyne–Brown Engr.…”
Section: Introductionmentioning
confidence: 99%
“…More recently, this restriction was removed by considering a large range in , and the coupled flow in the RSD was studied numerically with arbitrarily small surface shear viscosity. 9…”
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.
Development of experimental methods for in situ particle tracking velocimetry (PTV) is fundamental for allowing measurement of moving systems nontailored for velocimetry. This investigation focuses on the development of a post-processing methodology for single-camera PTV, without laser-sheet illumination, tracking native air-bubbles as tracer particles within a liquid drop of human insulin in microgravity. This PTV scenario was facilitated by microgravity technology known as the ring-sheared drop (RSD), aboard the International Space Station, which produced an optical imaging scenario and fluid flow geometry suitable as a testbed for PTV research. The post processing methodology performed included five steps: (i) physical system characterization and native air-bubble tracer identification, (ii) image projection and single-camera calibration, (iii) depth determination and 3D particle position determination, (iv) ray tracing and refraction correction, and (v) particle history and dataIn situ PTV in sheared drops expansion for suboptimal particles. Overall, this post processing methodology successfully allowed for a total of 1,085 particle measurements in a scenario where none were previously possible. Such post processing methodologies have promise for application to other in situ PTV scenarios allowing better understanding of physical systems whose flow is difficult to measure and or where PTV-specific optical elements (such as laser lights sheets and dual camera setups) are not permissible due to physical or safety constraints.
Fluid interfaces significantly influence the dynamics of protein solutions, effects that can be isolated by performing experiments in microgravity, greatly reducing the amount of solid boundaries present, allowing air-liquid interfaces to become dominant. This investigation examined the effects of protein concentration on interfacial shear-induced fibrillization of insulin in microgravity within a containerless biochemical reactor, the ring-sheared drop (RSD), aboard the international space station (ISS). Human insulin was used as a model amyloidogenic protein for studying protein kinetics with applications to in situ pharmaceutical production, tissue engineering, and diseases such as Alzheimer’s, Parkinson’s, infectious prions, and type 2 diabetes. Experiments investigated three main stages of amyloidogenesis: nucleation studied by seeding native solutions with fibril aggregates, fibrillization quantified using intrinsic fibrillization rate after fitting measured solution intensity to a sigmoidal function, and gelation observed by detection of solidification fronts. Results demonstrated that in surface-dominated amyloidogenic protein solutions: seeding with fibrils induces fibrillization of native protein, intrinsic fibrillization rate is independent of concentration, and that there is a minimum fibril concentration for gelation with gelation rate and rapidity of onset increasing monotonically with increasing protein concentration. These findings matched well with results of previous studies within ground-based analogs.
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