| Project/Area Number |
21K03878
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 19010:Fluid engineering-related
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| Research Institution | Kyushu University |
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Principal Investigator |
Wall Darren 九州大学, 工学研究院, 准教授 (30534309)
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| Project Period (FY) |
2021-04-01 – 2024-03-31
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| Project Status |
Granted (Fiscal Year 2021)
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| Budget Amount *help |
¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
Fiscal Year 2023: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2022: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2021: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
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| Keywords | Taylor-Dean flow / stratorotational / stratified flow / rotation / channel flow |
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| Outline of Research at the Start |
This research investigates the fundamental mechanisms that govern flows that feature shear, density stratification and are subject to a system rotation. We seek to thereby deepen understanding of such flows, which are ubiquitous in nature, and include accretion disks and atmospheric mesocyclones.
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| Outline of Annual Research Achievements |
This project focuses on the interaction of rotational stability mechanisms with those associated with density stratification. However, following the recent revelation that Rayleigh-stable flows can become unstable at sufficiently large Reynolds numbers (Deguchi Phys. Rev. E 95 021102(R) 2017), it was considered of interest to first explore and clarify this new instability mechanism, since it is not clear whether it is intrinsically related to curvature or rotation.
We are thus considering a Taylor-Dean flow, adopting a non-traditional mathematical formulation of this problem in which the effects of shear, curvature and rotation can be controlled. The problem is of interest for its own sake, but also permits an investigation of the interaction of this new mechanism with stratification.
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| Current Status of Research Progress |
Current Status of Research Progress
3: Progress in research has been slightly delayed.
Reason
In order to elucidate the mechanisms of the new instability mode we are adopting a non-traditional formulation of the problem that constructs dimensionless parameters that educe the essential dynamical mechanisms of the instability, i.e. shear, rotation and curvature (in contrast to a traditional formulation that uses parameters based on experimental controls such as cylinder rotation speeds). The present formulation requires a rotating frame of reference in contrast to the inertial frame employed in tradiitional approaches, and also requires the identification of appropriate scales for shear and curvature so as to cleanly educe the dynamics of the problem. The identification of an appropriate meaningful formulation took a little longer than anticipated, but has now been achieved.
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| Strategy for Future Research Activity |
Taylor-Dean Flow:
With the formulation complete, we are now deriving the perturbation equations. On completing this step, we will then construct a numerical code to solve the equations. After verifying the code we will then explore the four-dimensional parameter space to clarify the mechanism.
Stratorotational instability in planar Channel Flows:
We will then consider the stability of stratified planar channel flows subject to a system rotation. We will investigate flow in a Couette-Poiseuille configuration, extending previous studies.
A numerical code employing a Chebyshev collocation numerical technique will be constructed to solve the perturbation equations and verified against known special cases. The parameter space can then be explored, with research results disseminated.
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