2019 Fiscal Year Research-status Report
Wagging the tail: Elasticity and flexible filaments in microscopic flows
| Project/Area Number |
18K03958
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| Research Institution | Okinawa Institute of Science and Technology Graduate University |
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Principal Investigator |
HAWARD Simon 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 (20812986)
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| Project Period (FY) |
2018-04-01 – 2021-03-31
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| Keywords | microfluidics / complex fluids / rheology / flow instability / cylinder / fluid-structure |
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| Outline of Annual Research Achievements |
We are studying viscoelastic flows around microfluidic cylinders.
In FY2019, we have focused on 2 topics: (1) understanding a bistable viscoelastic flow asymmetry around the cylinders (first observed in FY2018), and (2) investigating fluid-structure interactions of viscoelastic fluids and flexible cylinders. Topic (1) was studied by a combination of experiment and numerical simulation with the clear conclusion that both shear-thinning of the fluid and high fluid elasticity are required for bistable asymmetric flows to occur. Topic (2) revealed how elastic flow instabilities interact with objects in the fluid, causing complex motions. We have shown how two objects in the flow behave synchronously due to the viscoelastic properties of the fluid.
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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 very well and possibly more smoothly than expected. In FY2018 some unexpected and novel phenomena were discovered. In FY2019, detailed experimentation and numerical modeling has enabled a clear understanding of these phenomena in terms of the fluid physical properties, the geometrical parameters of the microfluidic device and the imposed flow rates. We have also produced the the first example of viscoelastic fluid-structure interactions in a microfluidic flow and we discovered a startling synchronization occurs between the motion of multiple passive objects in the flow. This has motivated several series of experiments looking at how the synchronized motion depends on the precise locations of the objects inside the microfluidic device.
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| Strategy for Future Research Activity |
In FY2020, we plan two major experimental works examining the motions of multiple flexible cylinders immersed in a flowing viscoelastic fluid. In the first work we will study how the synchronization of two cylinders aligned along the flow axis depends on their separation. We suspect that different regimes of correlation will arise as the separation distance is varied. The second work will involve the study of coupled motions of flexible cylinders located side-by-side. Here, due to the onset of asymmetric flow around each of the cylinders (understood during FY2019 research), we anticipate extremely complex and interesting behaviour with multiple possible flow states arising. If time remains, we will fabricate ordered and/or random arrays of cylinders representing clusters of flexible cilia.
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