Conical shear-driven parametric instability of steady flow in precessing spheroids

Horimoto, Yasufumi; Katayama, Atsushi; Goto, Susumu

Physical Review Fluids, 2020, 5(6), 063901

Number of Access:25（2025-04-27 15:04 Counts）

Identifier to cite or link to this item: https://hdl.handle.net/11094/100044

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Title
Conical shear-driven parametric instability of steady flow in precessing spheroids
Creator
NRID
1000060822525 1000060822525
CreatorName
Horimoto, Yasufumi
CreatorName
Katayama, Atsushi
NRID
1000040321616 1000040321616
ORCID
0000-0001-7013-7967 0000-0001-7013-7967
researchmap permalink
read0193841 read0193841
Scopus Author ID
56040611400 56040611400
CreatorName
Goto, Susumu
Description
Horimoto Y., Katayama A., Goto S. Conical shear-driven parametric instability of steady flow in precessing spheroids. Physical Review Fluids 5, 063901 (2020); https://doi.org/10.1103/PhysRevFluids.5.063901.
Abstract
We investigate experimentally the instability of steady flow of fluid confined in weakly precessing spheroids. It is known that the conical-shear instability (CSI) proposed by Lin, Marti, and Noir [Phys. Fluids 27, 046601 (2015)] grows in a precessing sphere, and the elliptical and shearing instabilities [Kerswell, Geophys. Astrophys. Fluid Dyn. 72, 107 (1993)] can grow in precessing spheroids. Previous theories predict that when Re≲𝜂−5, where Re is the Reynolds number defined by the spin angular velocity and the equatorial radius of the spheroid and 𝜂 is its ellipticity, CSI dominates the other two instabilities even in a spheroid, and that, in particular, when 𝜂<0.17 the critical Poincaré number (i.e., the critical precession rate) Po(𝑐) is proportional to Re−3/10 for 200⁢𝜂−2≪Re≲𝜂−5. To experimentally verify these predictions, we measure a long time-series of fluid velocity to accurately estimate the power spectrum. Then, we determine Po(𝑐) as a function of Re and show the qualitative change of its scaling depending on 𝜂. Our experimental results perfectly support the theoretical predictions, implying that CSI can grow in precessing spheroids.
Publisher
American Physical Society
Source Title
Physical Review Fluids
Volume (Issue)
5(6)
Page
063901
Date of Issued
2020-06-16
Language
English
Handle URL
https://hdl.handle.net/11094/100044
eISSN
2469990X
Relation.isIdenticalTo
DOI (Publisher Version)
https://doi.org/10.1103/PhysRevFluids.5.063901
Access Rights
open access
CopyRight
Copyright 2020 by the American Physical Society
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Version of Record
Category
学術雑誌論文 Journal Article