Hydrodynamic interaction of spherical aerosol particles in a high intensity acoustic field

Tiwary, R.; Reethof, G.

doi:10.1016/s0022-460x(86)80309-1

Cited by 37 publications

(26 citation statements)

References 6 publications

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“…We observe that particles approach each other in the angular range of 0°<  <50° and repel each other in the angular range of 50°<  <90°. The results of our numerical simulation coincide with the analytical solution of Dianov et al [17] and the numerical results of Tiwary and Reethof [13], and contradict the analytical and numerical results of Gonzalez et al [14], in whose studies particles aligned perpendicularly to the direction of the sound wave do not experience any interaction.…”

Section: Influence Of the Main Parameters On Interaction Velocitysupporting

confidence: 50%

“…Many kinds of mechanisms, such as Brownian motion of aerosols, turbulent gas motion, and gravitational effect of aerosols, have been proposed as the refill mechanisms. However, the refill factor based on these mechanisms gives agglomeration rates several orders of magnitude lower than the experimentally observed rates [3,13,20]. Since the acoustic wake effect was revealed to play a significant role with micron-sized particles, some researchers [5,6,8,13,20] tried to use it as the major mechanism to explain the rapid refilling in acoustic agglomeration.…”

Section: Discussion Of the Computational Resultsmentioning

confidence: 99%

“…In the studies of Tiwary and Reethof [13,20], strong repulsion was found for most small Figure 12 The cycle-averaged trajectories of small particles around a core particle in 10 cycles. particles near a core particle.…”

Section: Discussion Of the Computational Resultsmentioning

confidence: 99%

“…It is shown that the two particles converged in the acoustic field and eventually collided. The solid line in Figure 3(a) is the particle trajectories calculated based on the average convergence velocity of the acoustic wake effect using equation (13). Figure 3(b) shows the particle trajectories calculated by our simulation and the particle cycle-averaged trajectories.…”

Section: Comparisons Between the Simulation And Experimentsmentioning

confidence: 99%

“…However, both models are limited to particles aligned along the direction of the sound wave. Tiwary and Reethof [13] calculated the trajectories of particles due to the acoustic wake effect using numerical methods by neglecting the unsteady term. They concluded that the interaction velocities could be a major mechanism for refilling the agglomeration volume during acoustic agglomeration.…”

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confidence: 99%

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Numerical simulation of acoustic wake effect in acoustic agglomeration under Oseen flow condition

et al. 2012

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We numerically simulate the hydrodynamic interaction of aerosol particles due to the acoustic wake effect under the Oseen flow condition. Attraction is found for two nearby particles with an orientation angle of 0 to 50° with respect to the acoustic field, and weak repulsion is found outside this range. Good agreement is obtained between the numerical results and experiments in the literature. We study the influence of particle size, sound wave frequency and the particle separation. The result shows that the acoustic wake effect plays a significant role in acoustic agglomeration. It could be either the major agglomeration mechanism of monodisperse aerosols or the major refill mechanism for polydisperse aerosols to supplement orthokinetic interaction. Acoustic agglomeration is a process in which intense sound waves produce relative motions and collisions among aerosol particles. It can significantly shift the particle size distribution of an aerosol from smaller to larger sizes in a short time of the order of 1 s. Acoustic agglomeration has potential use in air pollution control as an aerosol preconditioning process to enhance the performance of conventional particle filtering devices, which are inefficient for retaining particles smaller than 2.5 m [1]. Acoustic agglomeration is governed by complex interaction mechanisms. The most significant ones are orthokinetic and hydrodynamic interactions [2]. Orthokinetic interaction is the most obvious mechanism. Particles with different sizes are entrained differently into the oscillating motion of the medium because of the differences in particle inertia. The relative motion leads to the approach and collision between particles. In one acoustic cycle, each larger particle sweeps a certain volume by its motion relative to smaller particles, and collects all the smaller particles in it. This volume is defined as the agglomeration volume. The mechanism of orthokinetic interaction was well summarized by Mednikov [3] and improved by other researchers [4][5][6]. Nevertheless, this mechanism cannot explain agglomeration of monodisperse aerosols or the way in which the agglomeration volume is refilled once it is emptied after one cycle.Hydrodynamic mechanisms are those which produce particle interactions through the surrounding medium because of hydrodynamic forces and the asymmetry of the flow field around the particle [1]. These mechanisms are generally considered to be the main acoustic agglomeration mechanisms for monodisperse aerosols because they are also active for same-sized particles [7]. Hydrodynamic mechanisms mainly include mutual radiation pressure and the acoustic wake effect [5,6,8,9]. The mutual radiation pressure is the effect due to the nonlinear interactions produced between the particle scattering wave and the incident field. However, so far, there is still no experiment to confirm this effect as a cause of agglomeration, and theoretical studies show that the mutual radiation pressure is much less important than the acoustic wake effect in acoustic agglome...

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Section: Influence Of the Main Parameters On Interaction Velocitysupporting

confidence: 50%