scholarly journals Outer Acoustic Streaming Flow Driven by Asymmetric Acoustic Resonances

Micromachines ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 65
Author(s):  
Junjun Lei ◽  
Gaokun Zheng ◽  
Zhen Yao ◽  
Zhigang Huang
Keyword(s):  
Standing Wave ◽  
Slip Velocity ◽  
Acoustic Pressure ◽  
Acoustic Radiation ◽  
Acoustic Streaming ◽  
Acoustic Standing Wave ◽  
Acoustic Resonances ◽  
Streaming Flows ◽  
Limiting Velocity ◽  
Streaming Flow

While boundary-driven acoustic streaming resulting from the interaction of sound, fluids and walls in symmetric acoustic resonances have been intensively studied in the literature, the acoustic streaming fields driven by asymmetric acoustic resonances remain largely unexplored. Here, we present a theoretical and numerical analysis of outer acoustic streaming flows generated over a fluid–solid interface above which a symmetric or asymmetric acoustic standing wave is established. The asymmetric standing wave is defined by a shift of acoustic pressure in its magnitude, i.e., S0, and the resulting outer acoustic streaming is analyzed using the limiting velocity method. We show that, in symmetric acoustic resonances (S0 = 0), on a slip-velocity boundary, the limiting velocities always drive fluids from the acoustic pressure node towards adjacent antinodes. In confined geometry where a slip-velocity condition is applied to two parallel walls, the characteristics of the obtained outer acoustic streaming replicates that of Rayleigh streaming. In an asymmetric standing wave where S0 ≠ 0, however, it is found that the resulting limiting velocity node (i.e., the dividing point of limiting velocities) on the slip-velocity boundary locates at a different position to acoustic pressure node and, more importantly, is shown to be independent of S0, enabling spatial separation of acoustic radiation force and acoustic streaming flows. The results show the richness of boundary-driven acoustic streaming pattern variations that arise in standing wave fields and have potentials in many microfluidics applications such as acoustic streaming flow control and particle manipulation.

scholarly journals Investigation into the Effect of Acoustic Radiation Force and Acoustic Streaming on Particle Patterning in Acoustic Standing Wave Fields

Sensors ◽  
2017 ◽  
Vol 17 (7) ◽  
pp. 1664 ◽  
Author(s):  
Shilei Liu ◽  
Yanye Yang ◽  
Zhengyang Ni ◽  
Xiasheng Guo ◽  
Linjiao Luo ◽  
...  
Keyword(s):  
Standing Wave ◽  
Acoustic Radiation ◽  
Acoustic Streaming ◽  
Radiation Force ◽  
Acoustic Radiation Force ◽  
Wave Fields ◽  
Acoustic Standing Wave

Simulation of Acoustic Streaming in a Resonator

2004 ◽  
Author(s):  
Bakhtier Farouk ◽  
Murat K. Aktas
Keyword(s):  
Flow Field ◽  
Standing Wave ◽  
Oscillatory Flow ◽  
Stokes Equations ◽  
Acoustic Streaming ◽  
Flow Patterns ◽  
Vortical Flow ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Streaming Flow

Formation of vortical flow structures in a rectangular enclosure due to acoustic streaming is investigated numerically. The oscillatory flow field in the enclosure is created by the vibration of a vertical side wall of the enclosure. The frequency of the wall vibration is chosen such that a standing wave forms in the enclosure. The interaction of this standing wave with the horizontal solid walls leads to the production of Rayleigh type acoustic streaming flow patterns in the enclosure. All four walls of the enclosure considered are thermally insulated. The fully compressible form of the Navier-Stokes equations is considered and an explicit time-marching algorithm is used to explicitly track the acoustic waves. Numerical solutions are obtained by employing a highly accurate flux corrected transport (FCT) algorithm for the convection terms. A time-splitting technique is used to couple the viscous and diffusion terms of the full Navier-Stokes equations. Non-uniform grid structure is employed in the computations. The simulation of the primary oscillatory flow and the secondary (steady) streaming flows in the enclosure is performed. Streaming flow patterns are obtained by time averaging the primary oscillatory flow velocity distributions. The effect of the amount of wall displacement on the formation of the oscillatory flow field and the streaming structures are studied. Computations indicate that the nonlinearity of the acoustic field increases with increasing amount of the vibration amplitude. The form and the strength of the secondary flow associated with the oscillatory flow field and viscous effects are found to be strongly correlated to the maximum displacement of the vibrating wall. Total number of acoustic streaming cells per wavelength is also determined by the strength and the level of the nonlinearity of the sound field in the resonator.

scholarly journals Numerical Simulation of Boundary-Driven Acoustic Streaming in Microfluidic Channels with Circular Cross-Sections

Micromachines ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 240 ◽  
Author(s):  
Junjun Lei ◽  
Feng Cheng ◽  
Kemin Li
Keyword(s):  
Cross Sections ◽  
Acoustic Pressure ◽  
Outer Boundary ◽  
Acoustic Streaming ◽  
Microfluidic Channels ◽  
Two Dimensional ◽  
Resonant Frequencies ◽  
Pressure Fields ◽  
Rectangular Channels ◽  
Limiting Velocity

While acoustic streaming patterns in microfluidic channels with rectangular cross-sections have been widely shown in the literature, boundary-driven streaming fields in non-rectangular channels have not been well studied. In this paper, a two-dimensional numerical model was developed to simulate the boundary-driven streaming fields on cross-sections of cylindrical fluid channels. Firstly, the linear acoustic pressure fields at the resonant frequencies were solved from the Helmholtz equation. Subsequently, the outer boundary-driven streaming fields in the bulk of fluid were modelled while using Nyborg’s limiting velocity method, of which the limiting velocity equations were extended to be applicable for cylindrical surfaces in this work. In particular, acoustic streaming fields in the primary (1, 0) mode were presented. The results are expected to be valuable to the study of basic physical aspects of microparticle acoustophoresis in microfluidic channels with circular cross-sections and the design of acoustofluidic devices for micromanipulation.

PARTICLE TRANSPORT ACROSS BI-FLUID INTERFACE USING ACOUSTIC RADIATION FORCE

2010 ◽  
Vol 24 (13) ◽  
pp. 1397-1400
Author(s):  
YANG LIU ◽  
KIAN-MENG LIM
Keyword(s):  
Standing Wave ◽  
Flow System ◽  
Acoustic Radiation ◽  
Radiation Force ◽  
Acoustic Radiation Force ◽  
The Other ◽  
Acoustic Properties ◽  
Micro Particles ◽  
Acoustic Standing Wave ◽  
Micro Flow

A bi-fluid micro-flow system is proposed for separating particles from its original solvent and re-diluting them into another solvent simultaneously. In this micro-flow system, two different miscible solvents flow parallel to each other through a 2-inlet-2-outlet micro-channel, where an acoustic standing wave is set up. Due to the differences in acoustic properties of these solvents, the pressure node of the acoustic wave is shifted from the middle line of the channel. Under the action of the acoustic radiation force, particles with positive ϕ-factors are extracted from their original solvent and re-suspended into the other solvent, wherein the pressure node resides. Particles suspended in the new solvent are collected at one of the two outlets downstream. Experiments were conducted on a prototype using two aqueous solutions: deionized water and 40% glycerin aqueous solution with polystyrene micro-particles. The results show that under the action of the acoustic standing wave, most of the particles were successfully transported from its original solvent to the other solvent and collected at the outlet.

scholarly journals Streaming flow by oscillating bubbles: quantitative diagnostics via particle tracking velocimetry

2017 ◽  
Vol 820 ◽  
pp. 529-548 ◽  
Author(s):  
Rocío Bolaños-Jiménez ◽  
Massimiliano Rossi ◽  
David Fernandez Rivas ◽  
Christian J. Kähler ◽  
Alvaro Marin
Keyword(s):  
Particle Tracking ◽  
Acoustic Streaming ◽  
Three Dimensional ◽  
Theoretical Models ◽  
Flow Strength ◽  
Oscillating Bubbles ◽  
Linear Oscillation ◽  
The Stability ◽  
Streaming Flows ◽  
Streaming Flow

Oscillating microbubbles can be used as microscopic agents. Using external acoustic fields they are able to set the surrounding fluid into motion, erode surfaces and even to carry particles attached to their interfaces. Although the acoustic streaming flow that the bubble generates in its vicinity has been often observed, it has never been measured and quantitatively compared with the available theoretical models. The scarcity of quantitative data is partially due to the strong three-dimensional character of bubble-induced streaming flows, which demands advanced velocimetry techniques. In this work, we present quantitative measurements of the flow generated by single and pairs of acoustically excited sessile microbubbles using a three-dimensional particle tracking technique. Using this novel experimental approach we are able to obtain the bubble’s resonant oscillating frequency, study the boundaries of the linear oscillation regime, give predictions on the flow strength and the shear in the surrounding surface and study the flow and the stability of a two-bubble system. Our results show that velocimetry techniques are a suitable tool to make diagnostics on the dynamics of acoustically excited microbubbles.

The Concentration and Separation Of Blood Components Using Acoustic Radiation Force

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 3665-3665 ◽  
Author(s):  
Daniel R Kennedy ◽  
Tyler Gerhardson ◽  
Brianna Sporbert ◽  
Dane Mealey ◽  
Michael J Rust ◽  
...  
Keyword(s):  
Standing Wave ◽  
Flow Rate ◽  
Whole Blood ◽  
Blood Cells ◽  
Acoustic Radiation ◽  
The United States ◽  
Great Promise ◽  
The Novel ◽  
Blood Components ◽  
Acoustic Standing Wave

Abstract The concentration of whole blood has a wide spectrum of medical uses, especially in blood transfusions for patients suffering acute blood loss from trauma or surgery. However, current methods rely on centrifugation, which has a tendency to cause fragmentation and deformation of cells. Acoustic standing waves are considered to be a gentler means to concentrate blood cells, but generally suffer from flow rate limitations of >103fold, functioning only on the microscale. To address this issue, we have developed a novel ultrasound technology that works at the macroscale, enabling it to process flow rates that would typically be required to handle medically relevant volumes. In this study, we have applied the principles of acoustic radiation at the macroscale to re-concentrate 10X diluted porcine blood by trapping the blood cells within a standing wave, resulting in the clumping of cells and platelets, ultimately leading to enhanced gravitational settling. Complete blood counts were measured with a VetScan HM5 hematology analyzer. Using an acoustic force generated by power levels up to 25 Watts, no lysing was observed in any of the experiments. The inlet flow rate through the device was 16 ml/min, and the concentrate flow rate of the blood components was typically 1 ml/min. The transducer was a 2 MHz PZT-8 operating at 10 W, and it was oriented to create an acoustic standing wave perpendicular to the flow direction. Results indicate successful capture of red blood cells, white blood cells, and platelets with separation efficiencies in excess of 90% in a single pass. Furthermore, the blood components were all reconcentrated back to levels similar to those in whole blood. Subsequent experiments and conditions have allowed for the separation of blood components, suggesting that the future development of acoustic methods to perform blood re-concentration procedures such as erythropheresis, leukapheresis and plateletpheresis in a gentler manner than current methods holds great promise. With almost 15 million transfusions performed each year in the United States, this technology has the potential to make a significant impact on the medical community, particularly for treatment of critically ill patients. Additionally, the novel technology has also demonstrated performance in separating lipid particles from blood, thus indicating its utility for reducing the occurrence of lipid microemboli during re-transfusion of shed blood in cardiopulmonary bypass surgeries, which have been linked with post-operative neurocognitive complications. As a result, the novel acoustophoretic technology may become a general purpose platform for achieving separation in a variety of biomedical applications. Disclosures: Mealey: Flo Design Sonics: Employment. Lipkens:Flo Design Sonics: Equity Ownership.

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