Imperial College London
Alternate

Dr. Yongyun Hwang

Faculty of Engineering, Department of Aeronautics

Reader in Fluid Mechanics
 
 
 
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Contact

 

+44 (0)20 7594 5078y.hwang

 
 
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Location

 

337City and Guilds BuildingSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Fung:2020:10.1017/jfm.2020.684,
author = {Fung, L and Hwang, Y},
doi = {10.1017/jfm.2020.684},
journal = {Journal of Fluid Mechanics},
pages = {R2--1--R2--11},
title = {A sequence of transcritical bifurcations in a suspension of gyrotactic microswimmers in vertical pipe},
url = {http://dx.doi.org/10.1017/jfm.2020.684},
volume = {902},
year = {2020}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - Kessler (Nature, vol. 313, 1985, pp. 218–220) first showed that plume-like structures spontaneously appear from both stationary and flowing suspensions of gyrotactic microswimmers in a vertical pipe. Recently, it has been shown that there exist multiple steady, axisymmetric and axially uniform solutions to such a system (Bees & Croze, Proc. R. Soc. A, vol. 466, 2010, pp. 2057–2077). In the present study, we generalise this finding by reporting that a countably infinite number of such solutions emerge as the Richardson number increases. Linear stability, weakly nonlinear and fully nonlinear analyses are performed, revealing that each of the solutions arises from the destabilisation of a uniform suspension. The countability of the solutions is due to the finite flow domain, while the transcritical nature of the bifurcation is because of the cylindrical geometry, which breaks the horizontal symmetry of the system. It is further shown that there exists a maximum threshold of achievable downward flow rate for each solution if the flow is to remain steady, as varying the pressure gradient can no longer increase the flow rate from the solution. All of the solutions found are unstable, except for the one arising at the lowest Richardson number, implying that they would play a role in the transient dynamics in the route from a uniform suspension to the fully developed gyrotactic pattern.
AU  - Fung,L
AU  - Hwang,Y
DO  - 10.1017/jfm.2020.684
EP  - 1
PY  - 2020///
SN  - 0022-1120
SP  - 2
TI  - A sequence of transcritical bifurcations in a suspension of gyrotactic microswimmers in vertical pipe
T2  - Journal of Fluid Mechanics
UR  - http://dx.doi.org/10.1017/jfm.2020.684
UR  - https://www.cambridge.org/core/journals/journal-of-fluid-mechanics/article/sequence-of-transcritical-bifurcations-in-a-suspension-of-gyrotactic-microswimmers-in-vertical-pipe/E9D02870CD14AB742BAC68E4ED53D251
UR  - http://hdl.handle.net/10044/1/82303
VL  - 902
ER  -
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