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{Dunstan:2018:10.1103/PhysRevFluids.3.123102,
author = {Dunstan, J and Lee, K and Hwang, Y and Park, S and Goldstein, R},
doi = {10.1103/PhysRevFluids.3.123102},
journal = {Physical Review Fluids},
title = {Evaporation-driven convective flows in suspensions of non-motile bacteria},
url = {http://dx.doi.org/10.1103/PhysRevFluids.3.123102},
volume = {13},
year = {2018}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - We report a novel form of convection in suspensions of the bioluminescent marine bacterium Photobacterium phosphoreum. Suspensions of these bacteria placed in a chamber open to the air create persistent luminescent plumes most easily visible when observed in the dark. These flows are strikingly similar to the classical bioconvection pattern of aerotactic swimming bacteria, which create an unstable stratification by swimming upwards to an air-water interface, but they are a puzzle since the strain of P. phosphoreum used does not express flagella and therefore cannot swim. When microspheres were used instead of bacteria, similar flow patterns were observed, suggesting that the convective motion was not driven by bacteria but instead by the accumulation of salt at the air-water interface due to evaporation of the culture medium. Even at room temperature and humidity, and physiologically relevant salt concentrations, the water evaporation was found to be sufficient to drive convection patterns. To prove this hypothesis, experiments were complemented with a mathematical model that aimed to understand the mechanism of plume formation and the role of salt in triggering the instability. The simplified system of evaporating salty water was first studied using linear stability analysis, and then with finite element simulations. A comparison between these three approaches is presented. While evaporation-driven convection has not been discussed extensively in the context of biological systems, these results suggest that the phenomenon may be broadly relevant, particularly in those systems involving microorganisms of limited motility.
AU  - Dunstan,J
AU  - Lee,K
AU  - Hwang,Y
AU  - Park,S
AU  - Goldstein,R
DO  - 10.1103/PhysRevFluids.3.123102
PY  - 2018///
SN  - 2469-990X
TI  - Evaporation-driven convective flows in suspensions of non-motile bacteria
T2  - Physical Review Fluids
UR  - http://dx.doi.org/10.1103/PhysRevFluids.3.123102
UR  - http://hdl.handle.net/10044/1/66744
VL  - 13
ER  -
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