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Modelling of particle paths passing through an ultrasonic standing wave

Modelling of particle paths passing through an ultrasonic standing wave
Modelling of particle paths passing through an ultrasonic standing wave
Within an ultrasonic standing wave particles experience acoustic radiation forces causing agglomeration at the nodal planes of the wave. The technique can be used to agglomerate, suspend, or manipulate particles within a flow. To control agglomeration rate it is important to balance forces on the particles and, in the case where a fluid/particle mix flows across the applied acoustic field, it is also necessary to optimise fluid flow rate.
To investigate the acoustic and fluid forces in such a system a particle model has been developed, extending an earlier model used to characterise the 1-dimensional field in a layered resonator. In order to simulate fluid drag forces, CFD software has been used to determine the velocity profile of the fluid/particle mix passing through the acoustic device. The profile is then incorporated into a MATLAB model. Based on particle force components, a numerical approach has been used to determine particle paths. Using particle coordinates, both particle concentration across the fluid channel and concentration through multiple outlets are calculated.
Such an approach has been used to analyse the operation of a microfluidic flow-through separator, which uses a half wavelength standing wave across the main channel of the device. This causes particles to converge near the axial plane of the channel, delivering high and low particle concentrated flow through two outlets, respectively. By extending the model to analyse particle separation over a frequency range, it is possible to identify the resonant frequencies of the device and associated separation performance.
This approach will also be used to improve the geometric design of the microengineered fluid channels, where the particle model can determine the limiting fluid flow rate for separation to occur, the value of which is then applied to a CFD model of the device geometry.
radiation force, cfd, standing waves, concentration
0041-624X
319-324
Townsend, R.J.
0452b21c-a758-4d4a-925b-1511d9296d62
Hill, M.
0cda65c8-a70f-476f-b126-d2c4460a253e
Harris, N.R.
237cfdbd-86e4-4025-869c-c85136f14dfd
White, N.M.
c7be4c26-e419-4e5c-9420-09fc02e2ac9c
Townsend, R.J.
0452b21c-a758-4d4a-925b-1511d9296d62
Hill, M.
0cda65c8-a70f-476f-b126-d2c4460a253e
Harris, N.R.
237cfdbd-86e4-4025-869c-c85136f14dfd
White, N.M.
c7be4c26-e419-4e5c-9420-09fc02e2ac9c

Townsend, R.J., Hill, M., Harris, N.R. and White, N.M. (2004) Modelling of particle paths passing through an ultrasonic standing wave. Ultrasonics, 42 (1-9), 319-324. (doi:10.1016/j.ultras.2004.01.025).

Record type: Article

Abstract

Within an ultrasonic standing wave particles experience acoustic radiation forces causing agglomeration at the nodal planes of the wave. The technique can be used to agglomerate, suspend, or manipulate particles within a flow. To control agglomeration rate it is important to balance forces on the particles and, in the case where a fluid/particle mix flows across the applied acoustic field, it is also necessary to optimise fluid flow rate.
To investigate the acoustic and fluid forces in such a system a particle model has been developed, extending an earlier model used to characterise the 1-dimensional field in a layered resonator. In order to simulate fluid drag forces, CFD software has been used to determine the velocity profile of the fluid/particle mix passing through the acoustic device. The profile is then incorporated into a MATLAB model. Based on particle force components, a numerical approach has been used to determine particle paths. Using particle coordinates, both particle concentration across the fluid channel and concentration through multiple outlets are calculated.
Such an approach has been used to analyse the operation of a microfluidic flow-through separator, which uses a half wavelength standing wave across the main channel of the device. This causes particles to converge near the axial plane of the channel, delivering high and low particle concentrated flow through two outlets, respectively. By extending the model to analyse particle separation over a frequency range, it is possible to identify the resonant frequencies of the device and associated separation performance.
This approach will also be used to improve the geometric design of the microengineered fluid channels, where the particle model can determine the limiting fluid flow rate for separation to occur, the value of which is then applied to a CFD model of the device geometry.

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Published date: 2004
Keywords: radiation force, cfd, standing waves, concentration
Organisations: EEE

Identifiers

Local EPrints ID: 259268
URI: http://eprints.soton.ac.uk/id/eprint/259268
ISSN: 0041-624X
PURE UUID: 44cd7cab-7e65-4604-8334-c9a01d0506b4
ORCID for M. Hill: ORCID iD orcid.org/0000-0001-6448-9448
ORCID for N.R. Harris: ORCID iD orcid.org/0000-0003-4122-2219
ORCID for N.M. White: ORCID iD orcid.org/0000-0003-1532-6452

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Date deposited: 20 Apr 2004
Last modified: 15 Mar 2024 02:46

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Contributors

Author: R.J. Townsend
Author: M. Hill ORCID iD
Author: N.R. Harris ORCID iD
Author: N.M. White ORCID iD

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