Focusing in a quadrupole acoustic channel

TY - JOUR

T1 - Focusing in a quadrupole acoustic channel

AU - Vainshtein, P.

AU - Shapiro, M.

N1 - Funding Information: This research has been supported by the Technion V.P.R. Fund.

PY - 2009/8

Y1 - 2009/8

N2 - We investigate analytically and numerically focusing of aerosol micron-and-submicron size particles in the incompressible laminar flow in a three-dimensional quadrupole acoustic channel of hyperbolic cross-section. The fluid-particle interaction of micron-size non-diffusive particles is described by a linear drag force. Considering motion of diffusive submicron particles, we account for their random displacements. Focusing efficiency is investigated for variety of flow and particle parameters, expressed in terms of dimensionless groups, namely acoustic strength parameter β = 2 ps / ρf (ω r0)2, where ps is the amplitude of pressure oscillations generated at channel walls, ω is the circular frequency of the oscillations, r0 is the channel cross-sectional half-size, ρf is the fluid density; axial flow velocity parameter ΠU = U / ω r0, where U is the maximal velocity of the axial flow; and frequency parameter ω τ, where τ is Stokes relaxation time. It is shown that acoustic oscillations with frequency of about 1 kHz focus micron size particles on axial distance comparable to channel cross-sectional size. Submicron diffusive particles cannot be focused exactly at the channel axis owing to the adverse effect of Brownian motion leading to the diffusion broadening. It is shown that the achievable focusing width decreases with increasing the acoustic strength parameter.

AB - We investigate analytically and numerically focusing of aerosol micron-and-submicron size particles in the incompressible laminar flow in a three-dimensional quadrupole acoustic channel of hyperbolic cross-section. The fluid-particle interaction of micron-size non-diffusive particles is described by a linear drag force. Considering motion of diffusive submicron particles, we account for their random displacements. Focusing efficiency is investigated for variety of flow and particle parameters, expressed in terms of dimensionless groups, namely acoustic strength parameter β = 2 ps / ρf (ω r0)2, where ps is the amplitude of pressure oscillations generated at channel walls, ω is the circular frequency of the oscillations, r0 is the channel cross-sectional half-size, ρf is the fluid density; axial flow velocity parameter ΠU = U / ω r0, where U is the maximal velocity of the axial flow; and frequency parameter ω τ, where τ is Stokes relaxation time. It is shown that acoustic oscillations with frequency of about 1 kHz focus micron size particles on axial distance comparable to channel cross-sectional size. Submicron diffusive particles cannot be focused exactly at the channel axis owing to the adverse effect of Brownian motion leading to the diffusion broadening. It is shown that the achievable focusing width decreases with increasing the acoustic strength parameter.

KW - Acoustics

KW - Aerosol

KW - Channel

KW - Focusing

UR - http://www.scopus.com/inward/record.url?scp=67649607765&partnerID=8YFLogxK

U2 - 10.1016/j.jaerosci.2009.04.005

DO - 10.1016/j.jaerosci.2009.04.005

M3 - 文章

AN - SCOPUS:67649607765

SN - 0021-8502

VL - 40

SP - 707

EP - 719

JO - Journal of Aerosol Science

JF - Journal of Aerosol Science

IS - 8

ER -