2021 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, ポストドクトラルスカラー (50865954)
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| Project Period (FY) |
2020-04-01 – 2023-03-31
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| Keywords | Microfluidics / Complex fluids / Fluid mechanics / Viscoelasticity / Cylinder / Micelles / Instability / Polymers |
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| Outline of Annual Research Achievements |
Over the last two years, we have significantly expanded our understanding of how the flow of a viscoelastic fluid past an object in a microchannel can destabilize due fluid elasticity. For flow past a single cylinder, an elastic instability causes the fluid to randomly choose one of the two paths past the cylinder. In FY2020, we performed a detailed numerical and experimental study using different fluids to show that a suitible combination of shear-thinning viscosity and fluid elasticity are required for the instability to occur. We also discovered that if two cylinders are situated in the channel 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.
In FY2021, we sought to further our understanding of how the size of the cylinder affects the flow instability. We carried out a detailed, systematic study by varying the size of the cylinder while keeping the channel width constant. A phase diagram illustrating the flow behaviour as a function of flow rate and cylinder size was constructed. For a large enough cylinder, we found a novel instability where vortices form upstream of the cylinder attached to the wall. A detour was taken from the phase diagram work to perform a detailed study of this new phenomena and a paper has been submitted on it to Soft Matter and is now undergoing revisions. The remaining phase diagram work is now in the paper preparation stage and will be submitted in a few months.
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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
This project is in the final stages of being wrapped up. We discovered a new flow instability that occurs upstream of a cylinder if the cylinder is sufficiently large. We studied this phenomenon in detail and submitted a paper on it which is now undergoing revisions. The new discovery arose due to a systematic study on viscoelastic flow past a cylinder while varying the size of the cylinder. A paper on that work is now being prepared and will be submitted in a few months.
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| Strategy for Future Research Activity |
This research project is complete. Final work is being done to wrap up the projects. Two papers will hopefully be published within this fiscal year, and the results will be presented at the Society of Rheology meeting in October 2022.
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| Causes of Carryover |
The remainder was meant to be spent on travel and conference fees in FY2021, which did not happen for obvious reasons (COVID). It will be used in the next few months to pay publication fees.
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Research Products
(5 results)
