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Computational and experimental investigation of biofilm disruption dynamics induced by high velocity gas jet impingement

Computational and experimental investigation of biofilm disruption dynamics induced by high velocity gas jet impingement
Computational and experimental investigation of biofilm disruption dynamics induced by high velocity gas jet impingement

Experimental data showed that high-speed microsprays can effectively disrupt biofilms on their support substratum, producing a variety of dynamic reactions such as elongation, displacement, ripple formation, and fluidization. However, the mechanics underlying the impact of high-speed turbulent flows on biofilm structure is complex under such extreme conditions, since direct measurements of viscosity at these high shear rates are not possible using dynamic testing instruments. Here, we used computational fluid dynamics simulations to assess the complex fluid interactions of ripple patterning produced by high-speed turbulent air jets impacting perpendicular to the surface of Streptococcus mutans biofilms, a dental pathogen causing caries, captured by high-speed imaging. The numerical model involved a two-phase flow of air over a non-Newtonian biofilm, whose viscosity as a function of shear rate was estimated using the Herschel-Bulkley model. The simulation suggested that inertial, shear, and interfacial tension forces governed biofilm disruption by the air jet. Additionally, the high shear rates generated by the jet impacts coupled with shear-thinning biofilm property resulted in rapid liquefaction (within milli-seconds) of the biofilm, followed by surface instability and traveling waves from the impact site. Our findings suggest that rapid shear thinning under very high shear flows causes the biofilm to behave like a fluid and elasticity can be neglected. A parametric sensitivity study confirmed that both applied force intensity (i.e., high jet nozzle air velocity) and biofilm properties (i.e., low viscosity and low air-biofilm surface tension and thickness) intensify biofilm disruption by generating large interfacial instabilities.

Biofilm, computational fluid dynamics, high velocity air jets, non-Newtonian fluid flow, ripples, turbulence
2150-7511
Prades, Lledó
cc8d7389-5e3b-483c-994b-db6dc4ad8cc1
Fabbri, Stefania
c93b6166-2117-48a9-9a88-b23a62c7b5da
Dorado, Antonio
638706dd-48f8-409c-92f5-deec831c1ecf
Gamisans, Xavier
084b3669-eb5d-476d-b77a-4349d347c949
Stoodley, Paul
08614665-92a9-4466-806e-20c6daeb483f
Picioreanu, Cristian
aff88c97-ac54-464d-9338-a5bebf763d4a
Prades, Lledó
cc8d7389-5e3b-483c-994b-db6dc4ad8cc1
Fabbri, Stefania
c93b6166-2117-48a9-9a88-b23a62c7b5da
Dorado, Antonio
638706dd-48f8-409c-92f5-deec831c1ecf
Gamisans, Xavier
084b3669-eb5d-476d-b77a-4349d347c949
Stoodley, Paul
08614665-92a9-4466-806e-20c6daeb483f
Picioreanu, Cristian
aff88c97-ac54-464d-9338-a5bebf763d4a

Prades, Lledó, Fabbri, Stefania, Dorado, Antonio, Gamisans, Xavier, Stoodley, Paul and Picioreanu, Cristian (2020) Computational and experimental investigation of biofilm disruption dynamics induced by high velocity gas jet impingement. mBio, 11 (1), [e02813-19]. (doi:10.1128/mBio.02813-19).

Record type: Article

Abstract

Experimental data showed that high-speed microsprays can effectively disrupt biofilms on their support substratum, producing a variety of dynamic reactions such as elongation, displacement, ripple formation, and fluidization. However, the mechanics underlying the impact of high-speed turbulent flows on biofilm structure is complex under such extreme conditions, since direct measurements of viscosity at these high shear rates are not possible using dynamic testing instruments. Here, we used computational fluid dynamics simulations to assess the complex fluid interactions of ripple patterning produced by high-speed turbulent air jets impacting perpendicular to the surface of Streptococcus mutans biofilms, a dental pathogen causing caries, captured by high-speed imaging. The numerical model involved a two-phase flow of air over a non-Newtonian biofilm, whose viscosity as a function of shear rate was estimated using the Herschel-Bulkley model. The simulation suggested that inertial, shear, and interfacial tension forces governed biofilm disruption by the air jet. Additionally, the high shear rates generated by the jet impacts coupled with shear-thinning biofilm property resulted in rapid liquefaction (within milli-seconds) of the biofilm, followed by surface instability and traveling waves from the impact site. Our findings suggest that rapid shear thinning under very high shear flows causes the biofilm to behave like a fluid and elasticity can be neglected. A parametric sensitivity study confirmed that both applied force intensity (i.e., high jet nozzle air velocity) and biofilm properties (i.e., low viscosity and low air-biofilm surface tension and thickness) intensify biofilm disruption by generating large interfacial instabilities.

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Manuscript_Biofilm_mechanics_and_turbulent_flow_Prades_et_al_2019 PS - Accepted Manuscript
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Accepted/In Press date: 13 November 2019
e-pub ahead of print date: 7 January 2020
Additional Information: Funding Information: This work was financially funded in part by project CTQ2015-69802-C2-2-R (MINECO/ FEDER, UE). L. Prades was supported by grant BES-2013-066873 (FPI-2013, MINECO). P. Stoodley and S. Fabbri were supported in part by EPSRC DTP award EP/K503130/1 and in part by Philips Oral Healthcare, Bothell, WA, USA. Support was also provided by European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 676070 (C. Picioreanu). Publisher Copyright: © 2020 Prades et al.
Keywords: Biofilm, computational fluid dynamics, high velocity air jets, non-Newtonian fluid flow, ripples, turbulence

Identifiers

Local EPrints ID: 435892
URI: http://eprints.soton.ac.uk/id/eprint/435892
ISSN: 2150-7511
PURE UUID: 244cdbc6-b358-45c5-b829-035b7ccafec9
ORCID for Paul Stoodley: ORCID iD orcid.org/0000-0001-6069-273X

Catalogue record

Date deposited: 22 Nov 2019 17:30
Last modified: 02 Aug 2022 04:01

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Contributors

Author: Lledó Prades
Author: Stefania Fabbri
Author: Antonio Dorado
Author: Xavier Gamisans
Author: Paul Stoodley ORCID iD
Author: Cristian Picioreanu

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