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

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).

scholarly journals Aggregation kernel of globular inclusions in local shear flow: application to aggregation in a gas-stirred ladle

2019 ◽  
Vol 116 (5) ◽  
pp. 512 ◽  
Author(s):  
Matthieu Gisselbrecht ◽  
Jean-Sébastien Kroll-Rabotin ◽  
Jean-Pierre Bellot
Keyword(s):  
Particle Size ◽  
Shear Flow ◽  
Inclusion Size ◽  
Numerical Approach ◽  
Collision Kernel ◽  
Immersed Boundary ◽  
Inclusion Removal ◽  
Local Shear ◽  
Lagrangian Tracking ◽  
Hydrodynamic Effects

The control of metal cleanliness has always been a concern for metallurgists since inclusions directly influence the mechanical properties of alloys. In most metallurgical routes, a refining treatment of the liquid alloy is performed, in particular with the aim of improving the metal cleanliness that is achieved via a better control of particle contents and particle size. Since the efficiencies of inclusion removal mechanisms increase with inclusion size, the turbulent aggregation process plays a major role in all refining treatments. Interaction between particles such as aggregation is usually modelled through kinetics kernels which may be difficult to estimate. This paper contributes to express turbulent aggregation kernel taking into account the hydrodynamic effects at the inclusion scale. The numerical approach combines three numerical techniques, a Lattice Boltzmann Method to resolve the flow, an immersed boundary method for the particle-fluid interactions and a Lagrangian tracking for the motion of individual particles. Deterministic simulations of spherical particle pair trajectories leading to collision or avoidance allow us to calculate statistical kernels in a shear flow. The results show a strong influence of the short distance hydrodynamic effects on the collision kernel, particularly when the diameter ratio of the two interacting particles is far from unity. An application of this new aggregation kernel is applied to simulate the time evolution of the particle size distribution in a typical steel gas-stirred ladle.

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.

Lift correction model for local shear flow effect on wind turbine airfoils

2014 ◽  
Vol 65 ◽  
pp. 275-280 ◽  
Author(s):  
Kyung Seh Lee ◽  
Chin Hwa Chung ◽  
Je Hyun Baek
Keyword(s):  
Shear Flow ◽  
Wind Turbine ◽  
Correction Model ◽  
Flow Effect ◽  
Local Shear ◽  
Turbine Airfoils

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.

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