1,720,973 research outputs found
Numerical models for simulation of 3D acoustophoresis over vibrating plates (formation of Chladni pattern)
No full textData collected for research presented in paper "Formation of inverse Chladni patterns in liquids at microscale: roles of acoustic radiation and streaming-induced drag forces", published in Lei, J. Microfluid Nanofluid (2017) 21: 50. doi:10.1007/s10404-017-1888-5. A numerical model describing the three steps for simulation of 3D acoustophoresis over vibrating plates (formation of Chladni pattern) is included.
Funded by EPSRC (DTP 2016-2017, EP/N509747/1).</span
Formation of inverse Chladni patterns in liquids at microscale: roles of acoustic radiation and streaming‑induced drag forces
No full textWhile Chladni patterns in air over vibrating plates at macroscale have been well studied, inverse Chladni patterns in water at microscale have recently been reported. The underlying physics for the focusing of microparticles on the vibrating interface, however, is still unclear. In this paper, we present a quantitative three-dimensional study on the acoustophoretic motion of microparticles on a clamped vibrating circular plate in contact with water with emphasis on the roles of acoustic radiation and streaming-induced drag forces. The numerical simulations show good comparisons with experimental observations and basic theory. While we provide clear demonstrations of three-dimensional particle size-dependent microparticle trajectories in vibrating plate systems, we show that acoustic radiation forces are crucial for the formation of inverse Chladni patterns in liquids on both out-of-plane and in-plane microparticle movements. For out-of-plane microparticle acoustophoresis, out-of-plane acoustic radiation forces are the main driving force in the near-field, which prevent out-of-plane acoustic streaming vortices from dragging particles away from the vibrating interface. For in-plane acoustophoresis on the vibrating interface, acoustic streaming is not the only mechanism that carries microparticles to the vibrating antinodes forming inverse Chladni patterns: in-plane acoustic radiation forces could have a greater contribution. To facilitate the design of lab-on-a-chip devices for a wide range of applications, the effects of many key parameters, including the plate radius R and thickness h and the fluid viscosity μ, on the microparticle acoustophoresis are discussed, which show that the threshold in-plane and out-of-plane particle sizes balanced from the acoustic radiation and streaming-induced drag forces scale linearly with R and √μ, but inversely with √h
An investigation of boundary-driven streaming in acoustofluidic systems for particle and cell manipulation
No full textNumerical simulation of 3D acoustophoretic motion of microparticles in an acoustofluidic device
No full textAcoustic streaming is typically found in addition to acoustic radiation forces in acoustofluidic devices. Simulation of acoustic streaming is a crucial step for the understanding of its origins, which can provide efficient guidance on creating designs to limit or control this phenomenon. However, most existing methods can only simulate the streaming field in a local area, typically a cross-section of fluid channel. In this work, the three-dimensional (3D) Rayleigh streaming pattern in an acoustofluidic device is simulated and its effects on the movement of microparticles with various sizes are demonstrated. The viability of the simulation of 3D Rayleigh streaming presented here not only can provide better understanding and more comprehensive prediction of experiments in full acoustofluidic devices, but also can offer instructions on the simulation of unusual acoustic streaming patterns, e.g. transducer-plane streamin
Modelling and control of acoustic streaming in standing wave fields
No full textIn acoustofluidic particle manipulation and sorting devices streaming flows are typically found in addition to the acoustic radiation forces. Understanding their origins is essential for creating designs to limit or control this phenomenon.In addition to the classical Rayleigh streaming, experimental work from various groups has described ‘unusual’ acoustic streaming, transducer-plane streaming, typically a four-quadrant streaming pattern with the circulation parallel to the transducer face. The cause of this kind of streaming pattern has not been previously explained as it is different from the well-known classical streaming patterns such as Rayleigh streaming[1] and Eckart streaming[2].In this work, both 3D Rayleigh streaming and transducer-plane streaming are investigated using both experimental and numerical methods. Furthermore, acoustic streaming field due to two orthogonal standing wave fields in a microfluidic device is simulated and analysed
Acoustic streaming in the transducer plane in ultrasonic particle manipulation devices
No full textIn acoustofluidic manipulation and sorting devices, Rayleigh streaming flows are typically found in addition to the acoustic radiation forces. However, experimental work from various groups has described acoustic streaming that occurs in planar devices in a plane parallel to the transducer face. This is typically a four-quadrant streaming pattern with the circulation parallel to the transducer. Understanding its origins is essential for creating designs that limit or control this phenomenon. The cause of this kind of streaming pattern has not been previously explained as it is different from the well-known classical streaming patterns such as Rayleigh streaming and Eckart streaming, whose circulation planes are generally perpendicular to the face of the acoustic transducer. In order to gain insight into these patterns we present a numerical method based on Nyborg's limiting velocity boundary condition that includes terms ignored in the Rayleigh analysis, and verify its predictions against experimental PIV results in a simple device. The results show that the modelled particle trajectories match those found experimentally. Analysis of the dominant terms in the driving equations shows that the origin of this kind of streaming pattern is related to the circulation of the acoustic intensity
Dataset for the paper titled "Insights into transducer-plane streaming patterns in thin-layered acoustofluidic devices"
No full textData collected for research presented in paper "Insights into transducer-plane streaming patterns in thin-layered acoustofluidic devices". Physical Review Applied 2017
Funded by EPSRC Doctoral Training Partnership (EP/N509747/1).</span
Effects of surface profile on a boundary-driven acoustic streaming field
No full textAcoustic streaming fields in two-dimensional rectangular enclosures that have structured boundaries are simulated and the effects of surface profile amplitude on a boundary-driven acoustic streaming field are numerically investigated. The standing wave fields in the enclosures are generated by excitation of a boundary and a sine-wave shaped profile on a boundary parallel to the particle oscillations is considered. This surface profile is found to have a large influence on the magnitude of both outer and inner streaming velocities. In terms of streaming pattern, it is found that the number of inner streaming vortices is dependent on the wavelength of profile while this profile has a less significant effect on the outer vortex pattern
Modal Rayleigh-like streaming in layered acoustofluidic devices
No full textData collected for research presented in paper "Modal Rayleigh-like streaming in layered acoustofluidic devices" </span
Effects of surface profile on a boundary-driven acoustic streaming field
No full textControl of boundary-driven streaming in acoustofluidic systems is vital for various microfluidic applications either to generate it as a positive mechanism (e.g. microfluidic mixing, heat/mass transfer and fluid pumping) or suppressing it as an undesired disturbance (e.g. particle/cell focusing). It has been shown that two-dimensional (2D) and three-dimensional (3D) boundary-driven streaming can be solved from the limiting velocity method as long as the curvature of the surface is small compared to the viscous penetration depth. In this work, acoustic streaming fields in 2D rectangular enclosures that have structured textures, which do not satisfy this condition are numerically studied by full modelling of Reynolds stresses and the effects of surface profile amplitude on a boundary-driven acoustic streaming field are investigated. Specifically, a sine-wave shaped profile on a boundary parallel to the particle oscillations is considered, which is found to have large influences on both the magnitude of acoustic streaming velocities and streaming patterns
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