Motion of fluid-suspended fibres in a standing wave field

Brodeur, Pierre H.

doi:10.1016/0041-624x(91)90026-5

Cited by 23 publications

(17 citation statements)

References 15 publications

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“…Dahl et al (1990) experimentally studied the acoustic behavior of a flexible fibrous material consisted of cylindrically shaped aligned fibers. Brodeur (1991) presented a theoretical investigation on the motion of fluid-suspended fibers under the influence of a stationary ultrasonic wave field. Yasuda et al (1996)] investigated ultrasonically induced birefringence of two rod-like particles as a function of volume fraction, ultrasonic intensity, and frequency.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Viscoelastic and Multiple Scattering Effects in Fiber Suspensions

Hasheminejad

Alibakhshi

2006

Journal of Dispersion Science and Technology

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This study considers the most fundamental problem of 2-D acoustic scattering in fiber suspensions. It treats the interaction of a plane compressional sound wave with a cluster of two flexible fibers submerged in a boundless viscous fluid medium. The dynamic viscoelastic properties of the fibers and the viscosity of the surrounding fluid are rigorously taken into account in the solution of the problem. The translational addition theorem for cylindrical wave functions, the Havriliak-Negami model for viscoelastic material behaviors and the appropriate wave field expansions and the pertinent boundary conditions are employed to develop a closed-form solution in the form of an infinite series. The prime objectives are to investigate the influence of dynamic viscoelastic properties of fiber material as well as multiple scattering interaction effects on acoustic scattering and its associated quantities. The analytical results are illustrated with a numerical example in which two identical viscoelastic fibers are insonified by a plane sound wave at broadside/end-on incidence. The backscattering form function amplitude and the spatial distribution of the total acoustic pressure are numerically evaluated and discussed for representative values of the parameters characterizing the system. The effects of incident wave frequency, angle of incidence, material properties, and proximity of the two fibers are examined. A limiting case involving a pair of rigid cylinders in an ideal fluid is considered, and fair agreement with a well-known solution is established. INTRODUCTIONSuspensions of flexible filaments or rod-like particles in either Newtonian or non-Newtonian fluids are encountered in a wide range of industrial applications in the papermaking, chemical, petroleum, mining and food industries. In particular, there is a growing interest in using ultrasound as a basis for nondestructive evaluation of concentrated suspensions of fibers in solvents and polymers such as in paper pulp suspensions and fiber-reinforced resin-matrix materials. Attanasio et al. (1969) measured the complex shear modulus of dilute suspensions of cellulose fibers as a function of frequency in the low acoustic range. Lastinger (1972) made measurements of sound speed and absorption in water-saturated stainlesssteel fibrous metals and concluded that sound absorption was qualitatively in agreement with Urick's theory for suspensions. Adams (1977) investigated the use of ultrasonic propagation measurements for the purpose of estimating the physical properties of paper fiber suspensions. McQueen (1978) developed simple acoustic theory of wave motion in two component

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Section: Introductionmentioning

confidence: 99%

Dynamic Viscoelastic and Multiple Scattering Effects in Fiber Suspensions

Hasheminejad

Alibakhshi

2006

Journal of Dispersion Science and Technology

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“…Impedance matching between the acoustic transducer, the forming wire and the fiber mat is critical to the success of this technique. There is a fundamental impedance mismatch between the three components and the interaction between the three is driven by acoustic frequency and intensity, wire wetting (2,3), wire weave (4) and fiber geometry (5). This highly complex and non-linear interaction has been investigated experimentally (see appendix).…”

Section: Introductionmentioning

confidence: 99%

Acoustic Forming for Enhanced Dewatering and Formation

Aidun¹

2007

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and key words:The next generation of forming elements based on acoustic excitation to increase drainage and enhances formation both with on-line control and profiling capabilities has been investigated in this project. The system can be designed and optimized based on the fundamental experimental and computational analysis and investigation of acoustic waves in a fiber suspension flow and interaction with the forming wire. 2 PROJECT TITLE: ACOUSTIC FORMING FOR ENHANCED DEWATERING AND FORMATIONPRINCIPAL INVESTIGATOR: Cyrus K. Aidun, Professor, School of Mechanical Engineering, Georgia Institute of Technology, 500 10th St. NW, Atlanta, GA 30332-0620, (404) 894-6645, Fax 4778, cyrus.aidun@me,gatech.edu, Georgia 5th Congressional District. RESEARCH AREA(S) IN THE SOLICITATION TO WHICH THIS WORK IS FOCUSED: ENERGY PERFORMANCE, Area 1: New Approaches to Drying and Water Removal I. Executive SummaryWhen ultrasonic waves are applied to pulp fibers in a liquid suspension, the fibers move away from the source due to the acoustic force acting on the fibers. The acoustic force consists of three major forcing mechanisms acting on a fiber. These are acoustic radiation, acoustic streaming, and capitation bubble-induced force. These mechanisms are inter-dependent and nonlinear as well as frequency-dependent. It is the combination of all three forces that contributes to the manipulation of pulp fibers suspended in liquid. In this project we use this effect at the early stages of the forming table to generate controlled normal force on the fiber mat in the forming section to: (a) re-fluidize the fibers in the fiber mat to increase the drainage rate, (b) generate controlled activity on the forming wire to enhance formation, and (c) through sectional excitation, profile the sheet for more uniform moisture profile. The results have had limited success, as a large portion of the acoustic energy is dampened while crossing the porous wire. We have done substantial evaluation of acoustic transmission through the actual forming wires and have compiled a substantial data set from the experiments, as presented in the appendix. Through this project we have been able to develop a technology for enhanced dewatering and formation improvement in some grades of specialty paper where the value of the final product is large enough for a favorable cost-benefit process. II. IntroductionIn the forming section, foils and suction boxes are used for dewatering of the pulp suspension delivered from the headbox. As soon as the forming jet impinges on the forming board, a layer of concentrated fiber mat forms on the forming wire. It has been demonstrated that by re-fluidizing the fiber mat at the early stages of the forming table, the dewatering rate increases resulting in additional drainage capacity along the same length of the forming section. Furthermore, it is demonstrated that this action enhances formation of the sheet by generating additional activity on the wire with benefits in quality and fiber savings (1). This application is currently...

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“…Theoretical calculation of the acoustic radiation torque on a rigid rectangular disk was first proposed by Maidanik, in which the general expression was derived by an approach analogous to the radiation force [36]. Nowadays, the theory has been further developed with the influence of particle shape and material [37][38][39][40]44,48].…”

Section: Mechanical Effects On Microparticles In a Sound Fieldmentioning

confidence: 99%

“…Besides the conventional vortex-based rotation, controlling the object orientation is also achievable with this kind of acoustic torque. Changing the orientation of the sound field, by the manner of mechanically shifting the wave direction or modulating the wave parameters (amplitude or frequency), the fibers, and other non-spherical particles will be driven to rotate and finally reach an equilibrium angular position [38][39][40][41][42][43][44]. However, the resolution and controllability are limited for these demonstrated methods.…”

Section: Introductionmentioning

confidence: 99%

“…Particle rotation based on phase or frequency modulation strongly relies on the resonant modes of the employed acoustic chambers. So, the chamber should be elaborately designed with a proper Q-factor, which increases the system complexity and cost [38,[40][41][42][43]. In addition, it is difficult to maintain the rotation speed due to the amplitude variations of different modes.…”

Section: Introductionmentioning

confidence: 99%

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Controllable Micro-Particle Rotation and Transportation Using Sound Field Synthesis Technique

Deng

Jia

et al. 2018

Applied Sciences

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Rotation and transportation of micro-particles using ultrasonically-driven devices shows promising applications in the fields of biological engineering, composite material manufacture, and micro-assembly. Current interest in mechanical effects of ultrasonic waves has been stimulated by the achievements in manipulations with phased array. Here, we propose a field synthesizing method using the fewest transducers to control the orientation of a single non-spherical micro-particle as well as its spatial location. A localized acoustic force potential well is established and rotated by using sound field synthesis technique. The resultant acoustic radiation torque on the trapped target determines its equilibrium angular position. A prototype device consisting of nine transducers with 2 MHz center frequency is designed and fabricated. Controllable rotation of a silica rod with 90 µm length and 15 µm diameter is then successfully achieved. There is a good agreement between the measured particle orientation and the theoretical prediction. Within the same device, spatial translation of the silica rod can also be realized conveniently. When compared with the existing acoustic rotation methods, the employed transducers of our method are strongly decreased, meanwhile, device functionality is improved.

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Motion of fluid-suspended fibres in a standing wave field

Cited by 23 publications

References 15 publications

Dynamic Viscoelastic and Multiple Scattering Effects in Fiber Suspensions

Dynamic Viscoelastic and Multiple Scattering Effects in Fiber Suspensions

Acoustic Forming for Enhanced Dewatering and Formation

Controllable Micro-Particle Rotation and Transportation Using Sound Field Synthesis Technique

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