Direct measurement of small spherical particle rotation driven by the acoustic viscous torque

2020 ◽  
Vol 148 (4) ◽  
pp. 2709-2709
Author(s):  
Christoph Goering ◽  
Andreas Lamprecht ◽  
Iwan A. Schaap ◽  
Jürg Dual
Keyword(s):  
Spherical Particle ◽  
Direct Measurement ◽  
Particle Rotation ◽  
Small Spherical Particle ◽  
Viscous Torque

Determination of the generation cross section of a second harmonic on a small spherical particle

1975 ◽  
Vol 22 (3) ◽  
pp. 404-406
Author(s):  
Yu. A. Bykovskii ◽  
I. E. Nakhutin ◽  
�. A. Manykin ◽  
Yu. G. Rubezhnyi ◽  
P. P. Polu�ktov
Keyword(s):  
Spherical Particle ◽  
Cross Section ◽  
Second Harmonic ◽  
Small Spherical Particle

Apparatus for continuous, fast, and precise measurements of position and velocity of a small spherical particle

1983 ◽  
Vol 54 (12) ◽  
pp. 1643-1647 ◽  
Author(s):  
T. S. Venkataraman ◽  
William W. Eidson ◽  
Leonard D. Cohen ◽  
James D. Farina ◽  
Charles Acquista
Keyword(s):  
Spherical Particle ◽  
Small Spherical Particle

The motion of a dipolar spherical particle in homogeneous shear and time-periodic fields

1998 ◽  
Vol 369 ◽  
pp. 191-216 ◽  
Author(s):  
I. PUYESKY ◽  
I. FRANKEL
Keyword(s):  
External Field ◽  
Spherical Particle ◽  
Periodic Motion ◽  
Rotary Motion ◽  
Periodic Attractor ◽  
Particle Rotation ◽  
Frequency Locking ◽  
Homogeneous Shear ◽  
Global Time ◽  
Time Periodic

The effects of the intensity and frequency of a time-periodic external field on the rotary motion of a dipolar spherical particle suspended in homogeneous shear are studied with the goal of providing insight into problems concerning the motion of swimming microorganisms and the macroscopic behaviour of ferrofluids. The analysis reveals two modes of motion: convergence of the particle to a global time-periodic attractor, and quasi-periodic motion. The former mode of particle rotation generally appears for sufficiently strong fields. However, asymptotic analysis clarifies that it may occur even for very weak fields as a cumulative result of appropriate resonance interactions.A sufficient condition for the occurrence of a global time-periodic attractor is established for an external field acting in the plane of shear. Asymptotic results together with numerical evidence indicate that this condition is in fact a necessary condition as well. Making use of this condition we obtain the division of the plane of parameters into domains respectively corresponding to quasi-periodic motion and global time-periodic attractors. The latter domain has the structure of non-intersecting Arnold's tongues. Throughout each, the average frequency of dipole rotation about the vorticity vector is a constant (integral) multiple of the forcing frequency (frequency locking). In the case of quasi-periodic motion, there simultaneously coexist separate domains in orientation space where the rotary motion is locally characterized by different constant rotation numbers. These may assume both rational and irrational values. Potential implications of the distinction between these modes of rotary motion on the characterization of effective (macroscale) ferrofluid properties are briefly discussed.

Internal Distribution of Radiant Absorption in a Spherical Particle

1991 ◽  
Vol 113 (2) ◽  
pp. 407-412 ◽  
Author(s):  
A. Tuntomo ◽  
C. L. Tien ◽  
S. H. Park
Keyword(s):  
Refractive Index ◽  
Electromagnetic Wave ◽  
Spherical Particle ◽  
Complex Refractive Index ◽  
General Pattern ◽  
Wave Theory ◽  
Internal Field ◽  
Geometrical Optics ◽  
Small Spherical Particle ◽  
Internal Distribution

This paper applies electromagnetic wave theory for the study of the internal radiant absorption field of a small spherical particle, particularly to determine the optimum combination of size-to-wavelength parameter and complex refractive index for maximum local peak absorption. A map is devised to illustrate the general pattern of the internal field, which can be divided into three main regimes: uniform, front-concentrated, and back-concentrated absorption. In addition, the current study employs geometrical optics to investigate the internal field of radiant absorption. A comparison between the results from the geometrical optics approach to those from electromagnetic wave theory shows that the error involved in the geometrical optics approach increases sharply with the real part of the complex refractive index. A criterion is established to define the region of the applicability of geometrical optics.

Dynamics of a Small Spherical Particle in Steady Two-Dimensional Vortex Flows

1994 ◽  
Vol 47 (6S) ◽  
pp. S61-S69 ◽  
Author(s):  
Juan C. Lasheras ◽  
Kek-Kiong Tio
Keyword(s):  
Spherical Particle ◽  
Mass Density ◽  
Fluid Velocity ◽  
Stokes Number ◽  
Viscous Drag ◽  
Particle Inertia ◽  
Small Perturbations ◽  
Rankine Vortex ◽  
Small Spherical Particle ◽  
Limiting Case

The equation of motion of a small spherical particle in an isolated Rankine vortex is analyzed using an asymptotic scheme valid for the limiting case of small Stokes number St. The effects of particle inertia and added mass, gravity, the acceleration of the fluid, viscous drag, and the Basset history force are taken into consideration. For the case of an isolated Rankine vortex, the analysis shows that in the region where the fluid velocity is large enough, the viscous drag constrains the particle to move with a velocity equal to that of the fluid plus a perturbation of order St. This perturbative term incorporates the effects of gravity, the density difference between the particle and the fluid, and the local acceleration of the fluid. In the region where the fluid velocity is small, the particle moves with a velocity equal to the sum of the fluid velocity and the rising/settling velocity of the particle in still fluid, the effects of particle inertia and fluid acceleration appearing as small perturbations. Throughout the whole region of the flow, the effect of the Basset force always appears at higher order than the other forces acting on the particle and may, consequently, be neglected. The analysis also shows that a particle with a mass density greater than that of the fluid always escapes from the central region of the vortex, but a buoyant particle may be trapped by the equilibrium point located there.

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