共查询到20条相似文献,搜索用时 31 毫秒
1.
F. G. Mitri 《The European physical journal. E, Soft matter》2009,28(4):469-478
The partial wave series for the scattering of a high-order Bessel beam (HOBB) of acoustic quasi-standing waves by an air bubble
and fluid spheres immersed in water and centered on the axis of the beam is applied to the calculation of the acoustic radiation
force. A HOBB refers to a type of beam having an axial amplitude null and an azimuthal phase gradient. Radiation force examples
obtained through numerical evaluation of the radiation force function are computed for an air bubble, a hexane, a red blood
and mercury fluid spheres in water. The examples were selected to illustrate conditions having progressive, standing and quasi-standing
waves with appropriate selection of the waves’ amplitude ratio. An especially noteworthy result is the lack of a specific
vibrational mode contribution to the radiation force determined by appropriate selection of the HOBB parameters. 相似文献
2.
F.G. Mitri 《Annals of Physics》2008,323(7):1604-1620
Starting from the exact acoustic scattering from a sphere immersed in an ideal fluid and centered along the propagation axis of a standing or quasi-standing zero-order Bessel beam, explicit partial-wave representations for the radiation force are derived. A standing or a quasi-standing acoustic field is the result of propagating two equal or unequal amplitude zero-order Bessel beams, respectively, along the same axis but in opposite sense. The Bessel beam is characterized by the half-cone angle β of its plane wave components, such that β = 0 represents a plane wave. It is assumed here that the half-cone angle β for each of the counter-propagating acoustic Bessel beams is equal. Fluid, elastic and viscoelastic spheres immersed in water are treated as examples. Results indicate the capability of manipulating spherical targets based on their mechanical and acoustical properties. This condition provides an impetus for further designing acoustic tweezers operating with standing or quasi-standing Bessel acoustic waves. Potential applications include particle manipulation in micro-fluidic lab-on-chips as well as in reduced gravity environments. 相似文献
3.
F.G. Mitri 《Applied Acoustics》2010,71(5):470-6060
Using the partial-wave series for the acoustic scattering of a high-order Bessel beam (HOBB) of counterpropagating quasi-standing waves of variable half-cone angles, a generalized radiation force expression is obtained. The radiation force function, which is the radiation force per unit cross-sectional surface and unit characteristic energy density, is expressed in terms of the order m of the HOBB, the quasi-standing waves’ amplitudes Φ0 and Φ1, as well as the variable half-cone angles β1 and β2. The features of the theory include the ability to suppress two resonances as well as exploring a broad range of parameters related to the beam shape and mechanical properties of the spherical target. 相似文献
4.
F.G. Mitri 《Ultrasonics》2010,50(6):620-627
Objective
The present research examines the acoustic radiation force of axisymmetric waves incident upon a cylinder of circular surface immersed in a nonviscous fluid. The attempt here is to unify the various treatments of radiation force on a cylinder with arbitrary radius and provide a formulation suitable for any axisymmetric incident wave.Method and results
Analytical equations are derived for the acoustic scattering field and the axial acoustic radiation force. A general formulation for the radiation force function, which is the radiation force per unit energy density per unit cross-sectional surface, is derived. Specialized forms of the radiation force function are provided for several types of incident waves including plane progressive, plane standing, plane quasi-standing, cylindrical progressive diverging, cylindrical progressive converging and cylindrical standing and quasi-standing diverging waves (with an extension to the case of spherical standing and quasi-standing diverging waves incident upon a sphere).Significance and some potential applications
This study may be helpful essentially due to its inherent value as a canonical problem in physical acoustics. Potential applications include particle manipulation of cylindrical shaped structures in biomedicine, micro-gravity environments, fluid dynamics properties of cylindrical capillary bridges, and the micro-fabrication of new cylindrical crystals to better control light beams. 相似文献5.
F.G. Mitri 《Ultrasonics》2009,49(8):794-798
Background and objective
Particle manipulation using the acoustic radiation force of Bessel beams is an active field of research. In a previous investigation, [F.G. Mitri, Acoustic radiation force on a sphere in standing and quasi-standing zero-order Bessel beam tweezers, Annals of Physics 323 (2008) 1604–1620] an expression for the radiation force of a zero-order Bessel beam standing wave experienced by a sphere was derived. The present work extends the analysis of the radiation force to the case of a high-order Bessel beam (HOBB) of positive order m having an angular dependence on the phase ?.Method
The derivation for the general expression of the force is based on the formulation for the total acoustic scattering field of a HOBB by a sphere [F.G. Mitri, Acoustic scattering of a high-order Bessel beam by an elastic sphere, Annals of Physics 323 (2008) 2840–2850; F.G. Mitri, Equivalence of expressions for the acoustic scattering of a progressive high order Bessel beam by an elastic sphere, IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control 56 (2009) 1100–1103] to derive the general expression for the radiation force function YJm,st(ka,β,m), which is the radiation force per unit characteristic energy density and unit cross-sectional surface. The radiation force function is expressed as a generalized partial wave series involving the half-cone angle β of the wave-number components and the order m of the HOBB.Results
Numerical results for the radiation force function of a first and a second-order Bessel beam standing wave incident upon a rigid sphere immersed in non-viscous water are computed. The rigid sphere calculations for YJm,st(ka,β,m) show that the force is generally directed to a pressure node when m is a positive even integer number (i.e. YJm,st(ka,β,m)>0), whereas the force is generally directed toward a pressure antinode when m is a positive odd integer number (i.e. YJm,st(ka,β,m)<0).Conclusion
An expression is derived for the radiation force on a rigid sphere placed along the axis of an ideal non-diffracting HOBB of acoustic standing (or stationary) waves propagating in an ideal fluid. The formulation includes results of a previous work done for a zero-order Bessel beam standing wave (m = 0). The proposed theory is of particular interest essentially due to its inherent value as a canonical problem in particle manipulation using the acoustic radiation force of a HOBB standing wave on a sphere. It may also serve as the benchmark for comparison to other solutions obtained by strictly numerical or asymptotic approaches. 相似文献6.
Marston PL 《The Journal of the Acoustical Society of America》2007,122(6):3162-3165
Prior computations predict that fluid spheres illuminated by an acoustic Bessel beam can be subjected to a radiation force directed opposite the direction of beam propagation. The prediction of negative acoustic radiation force is extended to the cases of a solid poly(methylmethacrylate) PMMA sphere in water and an empty aluminum spherical shell in water. Compared with the angular scattering patterns for plane wave illumination, the scattering into the back hemisphere is suppressed when the radiation force is negative. This investigation may be helpful in the development of acoustic tweezers and in the development of methods for manipulating objects during space flight. 相似文献
7.
Marston PL 《The Journal of the Acoustical Society of America》2006,120(6):3518-3524
An expression is derived for the radiation force on a sphere placed on the axis of an ideal acoustic Bessel beam propagating in an inviscid fluid. The expression uses the partial-wave coefficients found in the analysis of the scattering when the sphere is placed in a plane wave traveling in the same external fluid. The Bessel beam is characterized by the cone angle beta of its plane wave components where beta=0 gives the limiting case of an ordinary plane wave. Examples are found for fluid spheres where the radiation force reverses in direction so the force is opposite the direction of the beam propagation. Negative axial forces are found to be correlated with conditions giving reduced backscattering by the beam. This condition may also be helpful in the design of acoustic tweezers for biophysical applications. Other potential applications include the manipulation of objects in microgravity. Islands in the (ka, beta) parameter plane having a negative radiation force are calculated for the case of a hexane drop in water. Here k is the wave number and a is the drop radius. Low frequency approximations to the radiation force are noted for rigid, fluid, and elastic solid spheres in an inviscid fluid. 相似文献
8.
We develop a model for calculating the radiation force on spherically symmetric multilayered particles based on the acoustic scattering approach. An expression is derived for the radiation force on a multilayered sphere centered on the axis of a Gaussian standing wave propagating in an ideal fluid. The effects of the sound absorption of the materials and sound wave on acoustic radiation force of a multilayered sphere immersed in water are analyzed, with particular emphasis on the shell thickness of every layer, and the width of the Gaussian beam. The results reveal that the existence of particle trapping behavior depends on the choice of the non-dimensional frequency ka, as well as the shell thickness of each layer. This study provides a theoretical basis for the development of acoustical tweezers in a Gaussian standing wave, which may benefit the improvement and development of acoustic control technology, such as trapping, sorting, and assembling a cell, and drug delivery applications. 相似文献
9.
Acoustic radiation force of a quasi-Gaussian beam imparted to a solid spherical scatterer in a fluid
V. Nikolaeva O. A. Sapozhnikov 《Bulletin of the Russian Academy of Sciences: Physics》2017,81(1):80-83
The radiation force generated upon the scattering of a quasi-Gaussian acoustic beam on a homo-geneous elastic sphere in a fluid is investigated. It is shown that the force depends nonmonotonically on the ratio between the sphere’s diameter and the beam’s waist. For a given beam power, the radiation force has its maximum value when the diameters are roughly egual to each other. This is due to the resonant excitation of shear waves on the sphere’s surface under the impact of acoustic wave in the surrounding fluid. 相似文献
10.
针对一定声场作用下自由空间中的球形粒子,首先分析了声散射过程中的吸收声功率、散射声功率和损失声功率以及三者之间的关系,并通过计算发现了由于参数选取不当导致的负吸收现象。接着从动量守恒定律出发推导了声辐射力的一般表达式,阐释了声辐射力与声能流之间的关系,并从理论和计算两方面验证了负向声辐射力的存在。当负向声辐射力产生时,声波的背向散射被抑制。在此基础上,进一步研究了粒子的偏心特性和流体的黏度这两种常见因素对负向声辐射力的影响。利用球函数的加法公式推导了偏心球的散射系数和声辐射力公式,结果显示偏心距离、粒子的材料等都会显著改变负向声辐射力的产生条件。在低频近似下,由于流体黏度附加的正向声辐射力是否能完全抵消原来的负向声辐射力将决定最终的声辐射力方向。该结果对利用负向声辐射力制成单行波声学镊子来实现对特定粒子的操控有着理论指导意义。 相似文献
11.
在理论和数值上研究柱面波对多层球的声辐射力.基于声波的散射理论,得到声辐射力的解析解,并给出数值仿真.结果表明:在特定的ka和kr0处,柱面行波的辐射力可以是负值(k是波数,a是多层球的半径,r0是多层球到声源的距离).随着kr0增加到无穷大,仿真结果退化为平面波的情形.对双层球而言,每层的相对厚度影响曲线共振峰的大小和位置,但对三层球而言没有显著影响.当最内层的介质换成空气时,由于声阻抗差异较大,共振峰更加明显.该研究可以为研发新一代单行波声束声学镊子提供理论指导,该技术在生物医学超声和材料科学领域有广泛的应用. 相似文献
12.
Acoustic plane progressive waves incident on a sphere immersed in a nonviscous fluid exert a steady force acting along the
direction of wave motion. It is shown here that when an elastic gold sphere is coated with a polymer-type (polyethylene) viscoelastic
layer, this force becomes a force of attraction in the long wavelength limit. Kinetic, potential and Reynolds stress energy
densities are defined and evaluated with and in the absence of absorption in the layer. Without absorption, the mechanical
energy density counteracts the Reynolds stress energy density, which causes a repulsive force. However, in the case of absorption,
the attractive force is predicted to be a physical consequence of a mutual contribution of both the mechanical and the Reynolds
stress energy densities. This condition provides an impetus for further designing acoustic tweezers operating with plane progressive
waves as well as fabricating polymer-coated gold particles for specific biophysical and biomedical applications. 相似文献
13.
通过声散射理论,将水中粒子的Bessel波束声散射场的分波序列(PWS)表达公式加以推广,进而推导出声辐射力的表达公式,获得了液体球及弹性球在Bessel波束下声辐射力的变化规律。通过观察不同散射角形态函数,可发现声辐射力的产生与粒子背向散射抑制程度有关。对于液体球粒子,球壳厚度及材料介质对粒子声辐射力有着重要的影响,同时Bessel波束波锥角越大,产生负声辐射力的可能性越大。对于弹性球和弹性单层壳粒子,声辐射力的产生与其本身的共振特征存在很大的关系。同时,通过改变球壳内介质及壳层厚度的方法,可增加产生的负声辐射力的频率范围及幅值强度. 相似文献
14.
Axial acoustic radiation force on a fluid sphere between two impedance boundaries for Gaussian beam
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《中国物理 B》2019,(3)
The acoustic radiation force on a fluid sphere immersed in water between two boundaries given by a Gaussian beam is theoretically and numerically investigated in this work. Based on the finite series method, the Gaussian beam is expressed in terms of Bessel function and a weighting parameter. The effects of the two boundaries concerned in our study is worked out by the image theory. This work also provides a reference when considering the effects of certain factors such as the radius of the sphere and the distance between the sphere and two boundaries. The contrast with the acoustic radiation force on a fluid sphere near only one boundary is also made in this paper. Our study can offer a theoretical basis for acoustics manipulation, acoustic sensors in the field of biomedical ultrasound and material science. 相似文献
15.
The radiation pressure forces on a sphere with radially symmetric properties are considered as functions of the sphere size with respect to the wavelength in the quasi-standing plane wave field with a constant frequency in the presence of loss in the inclusion. It is shown that the presence of loss in the inclusion positioned in an ideal fluid medium enhances the filtering properties of the traveling component of a quasistanding wave. With an increase in attenuation, the inclusion size intervals in which such a filtering is possible are progressively shifted toward the smaller wave size region. As the attenuation grows, this leads to the predominance of forces caused by the traveling component of the quasi-standing wave over the forces caused by its standing component even for small coefficients of traveling for a wide range of wave sizes of the inclusion. In turn, this effect determines the filtering properties of the quasi-standing wave. A numerical experiment is carried out to confirm the conclusions of the theoretical analysis. 相似文献
16.
The axial and transverse radiation forces on a fluid sphere placed arbitrarily in the acoustical field of Bessel beams of standing waves are evaluated. The three-dimensional components of the time-averaged force are expressed in terms of the beam-shape coefficients of the incident field and the scattering coefficients of the fluid sphere using a partial-wave expansion (PWE) method. Examples are chosen for which the standing wave field is composed of either a zero-order (non-vortex) Bessel beam, or a first-order Bessel vortex beam. It is shown here, that both transverse and axial forces can push or pull the fluid sphere to an equilibrium position depending on the chosen size parameter ka (where k is the wave-number and a the sphere’s radius). The corresponding results are of particular importance in biophysical applications for the design of lab-on-chip devices operating with Bessel beams standing wave tweezers. Moreover, potential investigations in acoustic levitation and related applications in particle rotation in a vortex beam may benefit from the results of this study. 相似文献
17.
Acoustic radiation force acting on elastic and viscoelastic spherical shells placed in a plane standing wave field 总被引:1,自引:0,他引:1
Mitri FG 《Ultrasonics》2005,43(8):681-691
The theory of the acoustic radiation force acting on elastic spherical shells suspended in a plane standing wave field is developed in relation to their thickness and the content of their hollow regions. The theory is modified to include the effect of a hysteresis type of absorption of compressional and shear waves in the material. The fluid-loading effect on the acoustic radiation force function Y(st) is analyzed as well. Results of numerical calculations are presented for a number of elastic and viscoelastic materials, with the hollow region filled with water or air. These results show how the damping due to absorption, the change of the interior fluid inside the shells' hollow regions, and the exterior fluid surrounding their structures, affect the acoustic radiation force. 相似文献
18.
A mean force exerted on a small rigid sphere by a sound wave in a viscous fluid is calculated. The force is expressed as a sum of drag force coming from the external steady flow existing in the absence of the sphere and contributions that are cross products of velocity and velocity derivatives of the incident field. Because of the drag force and an acoustic streaming generated near the sphere, the mean force does not coincide with the acoustic radiation pressure, i.e., the mean momentum flux carried by the sound field through any surface enclosing the sphere. If the sphere radius R is considerably smaller than the viscous wave penetration depth delta, the drag force can give the leading-order contribution (in powers of delta/R) to the mean force and the latter can then be directed against the radiation pressure. In another limit, delta< or =R, the drag force and acoustic streaming play a minor role, and the mean force reduces to the radiation pressure, which can be expressed through source strengths of the scattered sound field. The effect of viscosity can then be significant only if the incident wave is locally plane traveling. 相似文献
19.
In this article we introduce the concept of multifrequency radiation force produced by a polychromatic acoustic beam propagating in a fluid. This force is a generalization of dynamic radiation force due to a bichromatic wave. We analyse the force exerted on a rigid sphere by a plane wave with N frequency components. Our approach is based on solving the related scattering problem, taking into account the nonlinearity of the fluid. The radiation force is calculated by integrating the excess of pressure in the quasilinear approximation over the surface of the sphere. Results reveal that the spectrum of the multifrequency radiation force is composed of up to N(N−1)/2 distinct frequency components. In addition, the radiation force generated by plane progressive waves is predominantly caused by parametric amplification. This is a phenomenon due to the nonlinear nature of wave propagation in fluids. 相似文献
20.