2021 Fiscal Year Research-status Report
Micro-tomographic measurements of elastic turbulence
| Project/Area Number |
21K14080
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| Research Institution | Okinawa Institute of Science and Technology Graduate University |
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Principal Investigator |
CARLSON Daniel 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 (50896256)
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| Project Period (FY) |
2021-04-01 – 2023-03-31
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| Keywords | Microfluidics / elastic turbulence / micro-tomographic PIV / viscoelasticity / flow instability |
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| Outline of Annual Research Achievements |
The research targets for FY2021 were centered on developing the methodology for three-dimensional (3D) reconstruction of elastic turbulence (ET) and delineating the transition to ET in a given flow geometry. We have manufactured a novel device via laser-induced etching which permits a multi-scale study of ET over sequential micro-contractions. We have successfully leveraged micro-tomographic particle image velocimetry (PIV) of a dilute poly(acrylamide) flow to quantify the first spatiotemporal description of ET and relate the transition to ET to enhanced pressure drop across the geometry.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
Imaging flow through the device requires tight refractive index matching (RIM) between the glass device and the flow. We have formulated the optimal viscoelastic solutions to precisely achieve RIM with a desired solvent concentration of glycerol in water. To remove the solid from the 3D PIV reconstruction, we have developed a new masking protocol by aligning an x-ray micro-tomography of the device with the flow volume. We refined the experimental protocol for pressure measurements, which required the unplanned purchase of a pump unit. We show the transition from viscoelastic instability to ET, confirmed via spectral analysis of the pressure signal. In the ET state we have time-resolved flow fluctuations and found positive feedback between instability and streamline curvature.
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| Strategy for Future Research Activity |
Research has progressed more efficiently than expected, and we have partially met a goal of FY2022: relating ET local flow structures to pressure drop. Experiments are continuing to determine polymer stress feedback on the local flow field.
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| Causes of Carryover |
A target equipment model (oscilloscope) was determined to not be effective for this project, and we purchased a different oscilloscope. However, there was also an unplanned purchase of a fluid pump unit for better pressure measurements. The remaining balance will cover an open-access fee for publishing FY2021 results.
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