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2019 年度 実績報告書

交差の幾何学における流動不安定性

研究課題

研究課題/領域番号 17J00412
研究機関沖縄科学技術大学院大学

研究代表者

BURSHTEIN Noa Batia  沖縄科学技術大学院大学, 科学技術研究科, 特別研究員(DC1)

研究期間 (年度) 2017-04-26 – 2020-03-31
キーワードIntersecting flows / Vortex dynamics / Flow instabilities
研究実績の概要

This year, the focus was on exploring high Reynolds number flow within the cross-slot geometry. Our experimental observations reveal that above a certain critical flow rate (Reynolds number, Re) the flow becomes unstable and a steady vortex flow appears. We discover that by changing the aspect ratio of the cross-section of the geometry and the Re, we can control the number of vortices that appear in the flow field and their structure. We suggested a model based on previous studied to describe the velocity and vorticity profiles of the central vortex. When increasing the Re to a critical value we observed that the flow becomes unsteady and periodic with characteristic frequencies that depends on the aspect ratio of the geometry and on the imposed Re. We have characterized and explained the different mechanisms that govern the periodic fluctuations that are observed in this flow type and our results are supported with numerical simulations done by our collaborators. The manuscript for this work is currently being prepared for submission.
Additionally, at the PMMH lab at ESPCI, we studied the interaction between spherical particles (80 micrometers diameter polystyrene particles, 8% of channels width) and the vortex flow in the cross-slot geometry. Our observations reveal that for a Newtonian fluid the particles will be evenly distributed in the flow field, the particles swirl inside the vortical structure. When adding small amount of polymers, the particles will flow around the vortex and will not be able to swirl through the vortical structure.

現在までの達成度 (段落)

令和元年度が最終年度であるため、記入しない。

今後の研究の推進方策

令和元年度が最終年度であるため、記入しない。

  • 研究成果

    (2件)

すべて 2019

すべて 学会発表 (2件) (うち国際学会 1件、 招待講演 1件)

  • [学会発表] Inertioelastic effects on a spiral vortex flow instability2019

    • 著者名/発表者名
      Noa Burshtein
    • 学会等名
      Annual European Rheology Conference (AERC 2019), Portoroz, Slovenia
    • 国際学会
  • [学会発表] Exploring the parameter space around an inertial flow instability at a stagnation point2019

    • 著者名/発表者名
      Noa Burshtein
    • 学会等名
      Seminar at the Faculty of Engineering, University of Liverpool, Liverpool, UK
    • 招待講演

URL: 

公開日: 2021-01-27  

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