Acoustic streaming near a sharp structure and its mixing performance characterization

Zhang, Chuanyu; Guo, Xiao‐Feng; Brunet, Philippe; Costalonga, Maxime; Royon, Laurent

doi:10.1007/s10404-019-2271-5

Cited by 45 publications

(90 citation statements)

References 44 publications

(66 reference statements)

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“…Second, although both experiments [33,37] and simulations [35,42] confirm the AS intensity depends on the sharpness of the tip, none of them dissociates the tip angle α from the curvature diameter 2r c , as shown in Figs. 1(a) and 1(d), both of which being a sign of sharpness.…”

Section: Introductionmentioning

confidence: 89%

“…One of the particularities and main advantages of "sharp-edge AS" is that it is generated at relatively low frequency, typically in the kHz range. Meanwhile, the order of magnitude of the steady streaming velocity can even be comparable to the vibration velocity, hence up to several hun- dreds of mm/s [37]. Benefiting from this strong disturbance within the fluid, various applications using sharp structures streaming have been developed in microfluidics: mixing processes [35,38], bioparticle control [39,40], as well as various on-chip devices [34,41].…”

Section: Introductionmentioning

confidence: 99%

“…Such a vibration was indeed observed with high-speed imaging, and it raises the question of the adaptation of the sharp edge geometry to the prescribed frequency in order to ensure a resonance condition. In Zhang et al's study [37], an oscillating flow was prescribed to the whole fluid, which also generates strong streaming around the sharp tip but without the constraint of operating at a specific frequency. Although Ovchinnikov et al's study [42] suggests that both situations should in principle lead to similar streaming flows, the first-order fluid oscillations in both situations should be different from each other.…”

Section: Introductionmentioning

confidence: 99%

“…1(a) and 1(d), both of which being a sign of sharpness. The difficulty is that in practice, the microlithography techniques make these two quantities related to each other [37]. Therefore, numerical simulations could tackle this challenging question.…”

Section: Introductionmentioning

confidence: 99%

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Unveiling of the mechanisms of acoustic streaming induced by sharp edges

et al. 2020

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Acoustic waves can generate steady streaming within a fluid owing to the generation of viscous boundary layers near walls of typical thickness δ. In microchannels, the acoustic wavelength λ is adjusted to twice the channel width w to ensure a resonance condition, which implies the use of MHz transducers. Recently, though, intense acoustic streaming was generated by acoustic waves of a few kHz (hence with λ w), owing to the presence of sharp-tipped structures of curvature radius at the tip r c smaller than δ. The present study quantitatively investigates this sharp-edge acoustic streaming via the direct resolution of the full Navier-Stokes equation using the finite element method. The influence of δ, r c , and viscosity ν on the acoustic streaming performance is quantified. Our results suggest choices of operating conditions and geometrical parameters, in particular the dimensionless tip radius of curvature r c /δ and the liquid viscosity.

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Section: Introductionmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Unveiling of the mechanisms of acoustic streaming induced by sharp edges

et al. 2020

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“…Incidentally, it is remarkable that the streaming flow is related to the non-zero local curvature of the vibrating object. This is reminiscent of the streaming induced by acoustic fields in microchannels either around cylindrical or squared posts [21], or near sharp edges [22,23,24] which concentrate the streaming force.…”

Section: Introductionmentioning

confidence: 99%

Vortex elongation in outer streaming flows

et al. 2020

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We study the secondary time-averaged flow (streaming) generated by an oscillating cylinder immersed within a fluid, under high amplitude forcing so that inertial effects are significant. This streaming is decomposed into a viscous boundary layer flow where vorticity is created, and an outer flow of larger size. We operate under conditions of relatively low viscosity, so that the boundary layer is smaller than the object diameter. While for low Keulegan-Carpenter (KC) number (small enough amplitude), the size of the outer flow is typically that of the object, here we show that at large enough forcing, the outer flow stretches along the direction of the vibration by up to 8 times, while the flow still keeps its axial symmetry. We quantify the elongation through PIV measurements under an unprecedented range of frequency and amplitude, so that the streaming Reynolds number reaches values much larger than unity. The absence of significant unsteady component of vorticity outside the viscous boundary layer -and the fact that the length of elongation scales well with the streaming Reynolds number -suggest that the stretching should be due to the convection of stationary vorticity by the streaming flow itself.

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3D Acoustofluidics via Sub‐Wavelength Micro‐Resonators

Harley

Kolesnik

et al. 2022

Adv Funct Materials

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Precise acoustic micromanipulation is emerging as an important tool in biomedical research, where acoustic forces have the advantage of being contact‐free, label‐free, and biocompatible. Conventional acoustofluidic approaches, however, produce device‐scale effects that limit the ability to locally target acoustic energies at the microscale. In this study, we demonstrate an approach to generate designed and highly local acoustic fields using 3D resonant mass‐spring microstructures, achieving local acoustic field gradients on the order of microns, orders of magnitude smaller than the fluid wavelength. In doing so, rapid and spatially defined controllable micromanipulation, including particle capture, transport, and patterning using arbitrarily arranged micro‐resonator arrays is demonstrated. This sub‐wavelength, 3D acoustofluidic approach results in highly localized and defined micromanipulation, with potential applications across sample preparation, cell analysis, and diagnostics.

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Acoustic streaming near a sharp structure and its mixing performance characterization

Abstract: Acoustic streaming near a sharp structure and its mixing performance characterization, Microfluidics and Nanofluidics

Cited by 45 publications

References 44 publications

Unveiling of the mechanisms of acoustic streaming induced by sharp edges

Unveiling of the mechanisms of acoustic streaming induced by sharp edges

Vortex elongation in outer streaming flows

3D Acoustofluidics via Sub‐Wavelength Micro‐Resonators

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