2020 Fiscal Year Research-status Report
Purely Elastic Flow-induced Vibrations of Microcylinders : Viscoelastic Fluid-Structure Interaction in Microfluidics
| Project/Area Number |
20K14656
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| Research Institution | Okinawa Institute of Science and Technology Graduate University |
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Principal Investigator |
Hopkins Cameron 沖縄科学技術大学院大学, マイクロ・バイオ・ナノ流体ユニット, 研究員 (50865954)
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| Project Period (FY) |
2020-04-01 – 2022-03-31
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| Keywords | Microfluidics / Complex fluids / Fluid mechanics / Fluid-structure / Viscoelasticity / Cylinder / Micelles / Instability |
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| Outline of Annual Research Achievements |
The aim of this project is to study how viscoelastic fluids interact with objects in a microfluidic channel.
Substantial work has been done on viscoelastic flow past a cylinder. A flow instability causes the fluid to randomly choose one of the two paths past the cylinder. In FY2020, we further developed our understanding of this instability by performing a combined numerical and experimental study. Three different viscoelastic fluids were studied to reveal that both shear-thinning and elasticity are required for the instability to occur.
The primary achievement in FY2020 was the discovery that if two cylinders are oriented side-by-side, regions of bistability and tristability can be observed where the fluid can randomly choose to pass through one, or two, of the three available paths.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
The project is progressing smoothly, with a small detour from the original plan due to a new discovery. In FY2019, we were motivated to investigate the interaction of flexible objects due to a viscoelastic flow instability. An exploratory study of flow past two flexible side-by-side cylinders revealed unexpected behaviour. The flow instability caused the cylinders to be randomly pushed together, or spread apart. In FY2020 we studied this further by looking at flow past two fixed side-by-side cylinders, which resulted in the discovery of a novel tristability phenomenon. Motivated by this new discovery, we are now working on a series of experiments to study the fluid-structure interaction in channels with varying number of cylinders, cylinder radius, and relative positioning of the cylinders.
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| Strategy for Future Research Activity |
In FY2021, we are already immersed in a systematic study of how cylinder radius and channel size (i.e., cylinder stiffness and blockage ratio) affect the dynamics of the viscoelastic flow instability as well as the time-dependent oscillations of the cylinders. Initial results indicate that the flow instability is strongly, and unexpectedly, affected by varying the blockage ratio. Following this work, two other projects are planned. The first project will study how the time-dependent oscillations and synchronization of two cylinders aligned in the flow direction depends on their separation distance. The second project will investigate how two flexible side-by-side cylinders behave with varying separation distance, similar to the tristability project from FY2020.
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| Causes of Carryover |
The FY2020 remainder (22,074 yen) is due to an expense occurring (conference registration fee) around the fiscal year turnover, and the FY2021 budget being used instead of the FY2020 remainder.
The full yen amount has already been spent from the FY2021 budget on other research items. The remainder of the FY2021 budget will be used for open access publication fees and other consumable items needed to do the research.
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Research Products
(4 results)
