DRAG ON SOLID SPHERES AND BUBBLES

A novel theory is presented which allows, for the first time, the analytical description of small-angle scattering experiments on anisotropic shaped clusters of nanoparticles. Experimentally, silica-filled rubber which is deformed is used as an example. The silica can be modelled by solid spheres which form clusters. The experiments demonstrate that the clusters become anisotropic as a result of the deformation whereas the spheres are not affected. A comparison of the newly derived model function and the experiments provides, for the first time, microscopic evidence of the inhomogeneous deformation of clusters in the rubbery matrix.

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A mesoscopic model for compression of granular materials

EPJ Web of Conferences ◽

10.1051/epjconf/201818301054 ◽

2018 ◽

Vol 183 ◽

pp. 01054

Author(s):

Elisha Rejovitzky

Keyword(s):

Experimental Data ◽

Wave Propagation ◽

Granular Materials ◽

Mechanical Model ◽

Sound Speed ◽

Bulk Material ◽

High Sensitivity ◽

Water Fraction ◽

Protective Structures ◽

Solid Spheres

The design of protective structures often requires numerical modeling of shock-wave propagation in the surrounding soils. Properties of the soil such as grain-grading and water-fraction may vary spatially around a structure and among different sites. To better understand how these properties affect wave propagation we study how the meso-structure of soils affects their equation of state (EOS). In this work we present a meso-mechanical model for granular materials based on a simple representation of the grains as solid spheres. Grain-grading is prescribed, and a packing algorithm is used to obtain periodic grain morphologies of tightly packed randomly distributed spheres. The model is calibrated by using experimental data of sand compaction and sound-speed measurements from the literature. We study the effects of graingrading and show that the pressures at low strains exhibit high sensitivity to the level of connectivity between grains. At high strains, the EOS of the bulk material of the grains dominates the behavior of the EOS of the granular material.

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Preparation of hollow Fe3O4 spheres through a facile method and their applications

Functional Materials Letters ◽

10.1142/s1793604717500758 ◽

2017 ◽

Vol 10 (06) ◽

pp. 1750075 ◽

Cited By ~ 2

Author(s):

Xingping Wu ◽

Aiping Zhu ◽

Zhaodong Nan

Keyword(s):

Saturation Magnetization ◽

Ostwald Ripening ◽

Solvothermal Method ◽

Hollow Spheres ◽

Hollow Structure ◽

Solid Sphere ◽

Small Particles ◽

Potential Applications ◽

One Step ◽

Solid Spheres

Fe3O4 hollow microspheres with good dispersibility and high saturation magnetization were synthesized through a facile one-step solvothermal method. The formation mechanism of the hollow structure was studied by taking time-dependent experiments. Porous [Formula: see text]-FeOOH and [Formula: see text]-Fe2O3 nanosheets were firstly fabricated. Fe3O4 solid spheres aggregated by small particles were obtained from the transition of [Formula: see text]-FeOOH and [Formula: see text]-Fe2O3. Finally, the solid sphere is transferred to hollow sphere through Ostwald ripening. The maximum saturation magnetization of the hollow spheres is [Formula: see text][Formula: see text]emu/g, which is higher than some results reported in references. The Fe3O4 hollow spheres show potential applications in microwave absorption and photocatalysis.

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The transition from free to forced convection in mass transfer from solid spheres

AIChE Journal ◽

10.1002/aic.690060415 ◽

1960 ◽

Vol 6 (4) ◽

pp. 579-584 ◽

Cited By ~ 10

Author(s):

F. H. Garner ◽

J. M. Hoffman

Keyword(s):

Mass Transfer ◽

Forced Convection ◽

Solid Spheres

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Hydrodynamic Boundary Layers at Solid Wall—A Tool for Separation of Fine Solids

Colloids and Interfaces ◽

10.3390/colloids5010011 ◽

2021 ◽

Vol 5 (1) ◽

pp. 11

Author(s):

Ljubomir Nikolov

Keyword(s):

Relative Density ◽

Hydrodynamic Interaction ◽

Theoretical Study ◽

Solid Wall ◽

Separation Processes ◽

Starting Point ◽

Potential Applications ◽

Neutrally Buoyant ◽

Solid Walls ◽

Solid Spheres

A theoretical study is performed about the hydrodynamic interaction of fine species entrapped in the boundary layer (BL) at solid wall (plate). The key starting point is the analysis of the disturbance introduced by solid spheres in the background fluid flow. For a neutrally buoyant entity, the type of interaction is determined by the size of the spheres as compared to the thickness of the BL region. The result is granulometric separation of the solids inside the BL domain at the wall. The most important result in view of potential applications concerns the so-called small particles Rp < L/ReL5/4 (ReL is the Reynolds number of the background flow and Rp is the radius of the entrapped sphere). In the case of non-neutrally buoyant particles, gravity interferes with the separation effect. Important factor in this case is the relative density of the solid species as compared to this of the fluid. In view of further practical uses, particles within the range of Δρ/ρ < Fr2/ReL1/2 (Fr is Froude number and Δρ/ρ is the relative density of the entrapped solids) are systematically studied. The trajectories inside the BL region of the captured species are calculated. The obtained data show that there are preferred regions along the wall where the fine solids are detained. The results are important for the assessment of the general efficiency of entrapment and segregation of fine species in the vicinity of solid walls and have high potential for further design of industrial separation processes.

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