scholarly journals Simultaneous Visuarization of Tracer Particles and Depositing Solid Particles in a Turburent Shear Flow by Using Two CCD Cameras

1999 ◽  
Vol 19 (Supplement2) ◽  
pp. 201-204
Author(s):  
Toshikazu Suzaki ◽  
Mitsuru Tanaka ◽  
Yasushi Maeda ◽  
Yoshimichi Hagiwara
Keyword(s):  
Shear Flow ◽  
Solid Particles ◽  
Ccd Cameras ◽  
Tracer Particles

Migration of solid particles perpendicular to a local shear flow dueto local instabilities

AIAA Journal ◽  
1987 ◽  
Vol 25 (7) ◽  
pp. 1016-1018 ◽  
Author(s):  
M. Fichman ◽  
D. Pnueli
Keyword(s):  
Shear Flow ◽  
Solid Particles ◽  
Local Shear

Trajectories of charged tracer particles around a charged sphere in a simple shear flow

1994 ◽  
Vol 263 ◽  
pp. 185-206 ◽  
Author(s):  
A. S. Dukhin ◽  
T. G. M. Van De Ven
Keyword(s):  
Shear Flow ◽  
Simple Shear ◽  
Tracer Particle ◽  
Simple Shear Flow ◽  
Infinite Length ◽  
Charged Sphere ◽  
Neutral Particles ◽  
Tracer Particles ◽  
Two Parameters ◽  
Limiting Case

The trajectories of electrically charged tracer particles travelling around a charged sphere subjected to a simple shear flow have been calculated. This is a limiting case of the relative trajectories of two unequal-sized spheres when the radius ratio a1/a2 approaches zero. Until now these trajectories have been calculated by assuming the additivity of hydrodynamic and electrostatic forces, while neglecting the electroviscous coupling forces. These electroviscous forces are long range and can significantly alter the relative trajectories of spheres. When a1/a2 → 0, it is found that these trajectories depend on two parameters, α and β, which depend on the surface charge density of the tracer particle and the sphere. The relative trajectories of charged particles are qualitatively different from those of neutral particles. There exist six intervals of α-values for which the trajectories of the tracer particle show different features. Several new types of trajectory appear, besides the open and closed trajectories for neutral particles, which we refer to as uni- and bidirectional infinite length trajectories, uni- and bidirectional finite length trajectories, open returning trajectories, and prolate, oblate and circular closed trajectories. This richness of possible trajectories is the result of three electrokinetic phenomena, affecting particle motion: electro-osmotic slip, electrophoretic and diffusiophoretic motion.

scholarly journals Contact problems for particles in a shear flow

2010 ◽  
pp. 513-531
Author(s):  
Nicolas Verdon ◽  
Aline Lefebvre-Lepot ◽  
Laurent Lobry ◽  
Patrice Laure
Keyword(s):  
Shear Flow ◽  
Stokes Equations ◽  
Contact Problems ◽  
Numerical Approach ◽  
Solid Particles ◽  
Fictitious Domain ◽  
Particle Model ◽  
Fictitious Domain Method ◽  
2D And 3D ◽  
Number Of Particles

This paper focuses on improving the description of the contact between solid particles in a fluid flow. The numerical approach used is related to the fictitious domain method for the fluid–solid problem. It is associated to a gluey particle model in order to improve the behaviour of the particles during their contacts as a Lagrangian method is applied for their displacement. The numerical methodology is validated through 2D and 3D computations describing interactions of two particles in a shear flow. The results obtained show the ability of the scheme to recover the reversibility of the Stokes equations, even for 3D configurations. Finally, another example is studied with larger number of particles.

scholarly journals Rheology of a suspension of elastic particles in a viscous shear flow

2011 ◽  
Vol 687 ◽  
pp. 209-237 ◽  
Author(s):  
Tong Gao ◽  
Howard H. Hu ◽  
Pedro Ponte Castañeda
Keyword(s):  
Steady State ◽  
Shear Flow ◽  
Effective Viscosity ◽  
Circular Cross Section ◽  
Solid Particles ◽  
Simple Shear Flow ◽  
Arbitrary Lagrangian Eulerian ◽  
Viscous Shear ◽  
Elastic Particles ◽  
Steady State Solutions

AbstractIn this paper we consider a suspension of elastic solid particles in a viscous liquid. The particles are assumed to be neo-Hookean and can undergo finite elastic deformations. A polarization technique, originally developed for analogous problems in linear elasticity, is used to establish a theory for describing the finite-strain, time-dependent response of an ellipsoidal elastic particle in a viscous fluid flow under Stokes flow conditions. A set of coupled, nonlinear, first-order ODEs is obtained for the evolution of the uniform stress fields in the particle, as well as for the shape and orientation of the particle, which can in turn be used to characterize the rheology of a dilute suspension of elastic particles in a shear flow. When applied to a suspension of cylindrical particles with initially circular cross-section, the theory confirms the existence of steady-state solutions, which can be given simple analytical expressions. The two-dimensional, steady-state solutions for the particle shape and orientation, as well as for the effective viscosity and normal stress differences in the suspension, are in excellent agreement with direct numerical simulations of multiple-particle dispersions in a shear flow obtained by using an arbitrary Lagrangian–Eulerian (ALE) finite element method (FEM) solver. The corresponding solutions for the evolution of the microstructure and the rheological properties of suspensions of initially spherical (three-dimensional) particles in a simple shear flow are also obtained, and compared with the results of Roscoe (J. Fluid Mech., vol. 28, 1967, pp. 273–293) in the steady-state regime. Interestingly, the results show that sufficiently soft elastic particles can be used to reduce the effective viscosity of the suspension (relative to that of the pure fluid).

A Study of Strong Shear Flow in a Narrow Gap of an Atomization Equipment

2008 ◽  
Author(s):  
Michihisa Tsutahara ◽  
Kenichi Hashimoto ◽  
Akira Michiwaki ◽  
Yuuichi Masuda ◽  
Masakazu Enomura ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Shear Flow ◽  
Rotating Disk ◽  
Rotating Cylinder ◽  
Cylindrical Vessel ◽  
Solid Particles ◽  
Narrow Gap ◽  
Rotating Disks ◽  
Rapid Rotation ◽  
Strong Shear

The mechanism of solid particle atomization by strong shear flow inside a narrow gap between a still disk and a rapidly rotating disk of a new beadless disperser called SS5 is clarified. We show that the solid particles rotate at the same rate as fluid particles, that is the angular velocity is a half of the vorticity using a equipment consisting of a rotating cylinder inside a cylindrical vessel, instead of rotating disks. The cavitation is shown to occur inside the gap and the mechanism of atomization of solid particles is considered to be due to the cavitation collapse. The cavitation generation is also considered to be promoted by the rapid rotation of the particles due to the strong shear and also by the pressure drop due to the centrifugal force driven by the rotation of the disk.

Morphological Evolution of SCN Crystals in a Shear Flow

2014 ◽  
Vol 217-218 ◽  
pp. 83-90
Author(s):  
Mehdi Reisi ◽  
Behzad Niroumand ◽  
Ebrahim Shirani
Keyword(s):  
Shear Flow ◽  
Morphological Evolution ◽  
Solid Particles ◽  
High Shear ◽  
Shear Rates ◽  
High Shear Rates ◽  
Cluster Morphology ◽  
Size And Morphology ◽  
Low Shear

Morphological evolution of a transparent model succinonitrile (SCN) material during solidification was investigated in an apparatus resembling a shearing-disc viscometer. The in situ microscopic observations showed that fragmentation decreased the average particles size, but did not result in transition of dendritic to spherical morphology. At low shear rates, the degenerated dendrites and at high shear rates, the pseudo-cluster morphology was observed. It was revealed that coarsening has the most important effect on the final morphology of solid particles. The quantitative influences of shearing rate and intensity on the size and morphology of solid crystals were also discussed based on the measurements on the microstructures.

Formation and growth of solid particles in shear flow

1990 ◽  
Vol 25 (4) ◽  
pp. 2185-2187 ◽  
Author(s):  
Wang Nan ◽  
Shu Guangji ◽  
Yang Hanguo
Keyword(s):  
Shear Flow ◽  
Solid Particles

scholarly journals TURBULENT BEHAVIOR OF FLUIDIZED SEDIMENTS IN COMPOSITE SHEAR FLOW

2011 ◽  
Vol 1 (32) ◽  
pp. 7 ◽  
Author(s):  
Ayumi Saruwatari ◽  
Wataru Matsuzaki ◽  
Yasunori Watanabe
Keyword(s):  
Shear Flow ◽  
Underlying Mechanism ◽  
Refraction Index ◽  
Suspended Solid ◽  
Solid Particles ◽  
Turbulent Shear ◽  
Turbulent Shear Flow ◽  
Fluid Medium ◽  
Particle Imaging ◽  
Bed Material

A particle imaging measurement of granular particles was applied to fluidized and suspended solid particles involved in steady and unsteady shear flows. In this measurement, 42% sodium iodide solution was used as a fluid medium to coincide the refraction index with the transparent bed material (silica gel). Therefore, the vertical distributions of the granular velocity and turbulent behavior within the bed can be measured by tracking the dyed particles mixed with the bed material. The turbulent kinetic energy in the fluidized layer and particle concentration can also be measured using this technique. The turbulence developed over the bed disturbed the bed material, and as a result the surface particles were lifted and suspended. The underlying mechanism of fluidization and suspension of the sediment seabed in complex turbulent shear flow is believed to be understood through further parametric studies based on the present imaging technique.

Measurement of Liquid Flow Field Using Micro Bubbles Instead of Solid Particles

2007 ◽  
Author(s):  
Hisato Minagawa ◽  
Satoshi Yamada ◽  
Takashi Terada
Keyword(s):  
Circular Cylinder ◽  
Flow Field ◽  
Velocity Profile ◽  
Liquid Flow ◽  
Average Diameter ◽  
Solid Particles ◽  
Square Cavity ◽  
Dissolution Method ◽  
Tracer Particles ◽  
General Size

The authors have studied for the effect of supplying oxygen into water with micro bubbles produced by the shearing method, and found that the micro bubbles are very effective for the oxygen supplying compared with general size bubbles. We also generate micro bubbles which make water cloudy through the pressurizing dissolution method. The average diameter of micro bubbles generated with this method is about 40 micro meters in our laboratory. They are much smaller than those produced by the shearing method, and are the similar size to the tracer or the reflector used to measure the flow field by the PIV or the UVP (Ultrasonic Velocity Profile monitor). Moreover, they are very economical and ecological compared with solid tracer particles. Therefore, we examine to apply micro bubbles generated with the pressurizing dissolution method to the measurement of liquid flow field using the PIV or the UVP. A flow in a square cavity at Re = 1000 was measured using the PIV and the UVP. We could recognize a clear vortex. A flow around a circular cylinder was also measured using the PIV. We can recognize the possibility of micro bubbles for these applications.

Sign in / Sign up

Export Citation Format

Share Document