The Central Role of Interparticle Forces in Colloidal Processing of Ceramics

2016 ◽  
pp. 147-170
Keyword(s):  
Colloidal Processing ◽  
Interparticle Forces

Role of interparticle forces during stress-induced agglomeration of CMP slurries

2011 ◽  
Vol 389 (1-3) ◽  
pp. 33-37 ◽  
Author(s):  
Feng-Chi Chang ◽  
Purushottam Kumar ◽  
Rohit Singh ◽  
Kannan Balasundaram ◽  
Jaeseok Lee ◽  
...  
Keyword(s):  
Interparticle Forces

Role of Interparticle Forces in the Formation of Random Loose Packing

2006 ◽  
Vol 96 (14) ◽  
Author(s):  
K. J. Dong ◽  
R. Y. Yang ◽  
R. P. Zou ◽  
A. B. Yu
Keyword(s):  
Interparticle Forces ◽  
Loose Packing

Hydrodynamic diffusion in active microrheology of non-colloidal suspensions: the role of interparticle forces

2015 ◽  
Vol 785 ◽  
pp. 189-218 ◽  
Author(s):  
N. J. Hoh ◽  
R. N. Zia
Keyword(s):  
Brownian Motion ◽  
External Force ◽  
Hydrodynamic Limit ◽  
Thermal Fluctuations ◽  
Longitudinal Force ◽  
Experimental Measurements ◽  
Interparticle Forces ◽  
Pair Density ◽  
Far From Equilibrium

Hydrodynamic diffusion in the absence of Brownian motion is studied via active microrheology in the ‘pure-hydrodynamic’ limit, with a view towards elucidating the transition from colloidal microrheology to the non-colloidal limit, falling-ball rheometry. The phenomenon of non-Brownian force-induced diffusion in falling-ball rheometry is strictly hydrodynamic in nature; in contrast, analogous force-induced diffusion in colloids is deeply connected to the presence of a diffusive boundary layer even when Brownian motion is very weak compared with the external force driving the ‘probe’ particle. To connect these two limits, we derive an expression for the force-induced diffusion in active microrheology of hydrodynamically interacting particles via the Smoluchowski equation, where thermal fluctuations play no role. While it is well known that the microstructure is spherically symmetric about the probe in this limit, fluctuations in the microstructure need not be – and indeed lead to a diffusive spread of the probe trajectory. The force-induced diffusion is anisotropic, with components along and transverse to the line of external force. The latter is identically zero owing to the fore–aft symmetry of pair trajectories in Stokes flow. In a naïve first approach, the vanishing relative hydrodynamic mobility at contact between the probe and an interacting bath particle was assumed to eliminate all physical contribution from interparticle forces, whereby advection alone drove structural evolution in pair density and microstructural fluctuations. With such an approach, longitudinal force-induced diffusion vanishes in the absence of Brownian motion, a result that contradicts well-known experimental measurements of such diffusion in falling-ball rheometry. To resolve this contradiction, the probe–bath-particle interaction at contact was carefully modelled via an excluded annulus. We find that interparticle forces play a crucial role in encounters between particles in the hydrodynamic limit – as they must, to balance the advective flux. Accounting for this force results in a longitudinal force-induced diffusion $D_{\Vert }=1.26aU_{S}{\it\phi}$, where $a$ is the probe size, $U_{S}$ is the Stokes velocity and ${\it\phi}$ is the volume fraction of bath particles, in excellent qualitative and quantitative agreement with experimental measurements in, and theoretical predictions for, macroscopic falling-ball rheometry. This new model thus provides a continuous connection between micro- and macroscale rheology, as well as providing important insight into the role of interparticle forces for diffusion and rheology even in the limit of pure hydrodynamics: interparticle forces give rise to non-Newtonian rheology in strongly forced suspensions. A connection is made between the flow-induced diffusivity and the intrinsic hydrodynamic microviscosity which recovers a precise balance between fluctuation and dissipation in far from equilibrium suspensions; that is, diffusion and drag arise from a common microstructural origin even far from equilibrium.

scholarly journals Experimental observations of fluidized beds at high temperatures

2016 ◽  
Vol 1 (1) ◽  
pp. 9 ◽  
Author(s):  
Paola Lettieri ◽  
David Newton ◽  
John G. Yates
Keyword(s):  
High Temperatures ◽  
Dominant Role ◽  
Effect Of Temperature ◽  
Interparticle Forces ◽  
Collapse Time ◽  
Experimental Values ◽  
Increasing Temperature ◽  
Fcc Catalysts

<p>The objective of this paper is to report some experimental observations on the effect of temperature on the fluidization of three fresh FCC catalysts and an equilibrium (E-cat) FCC. The bed collapse test was used as a quantitative test to characterise the <em>fluidization quality </em>of these materials with increasing temperatures. It provides a sensitive and discriminating means of assessing the changes in the materials’ responses between low and high temperature fluidization. The standardised collapse time, SCT, was calculated from the collapse profiles and the experimental values obtained for the FCC catalysts are reported in this paper. The fluidization quality of the fresh FCC catalysts improved with increasing temperature, as indicated by the increase in SCT values. On the other hand, the standardised collapse time of the E-cat FCC decreased with increasing temperature as the catalyst became less aeratable. Changes of the surface properties of this material occurred on increasing temperature. The flow behaviour of the E-cat catalyst was compared with fluidization of a Group C material. The aeratability of this latter material decreased exponentially, due to the dominant role of the interparticle forces over the hydrodynamic forces, with increasing temperature. The use of classical concepts such as the non bubbling ratio, u<sub>mb</sub>/u<sub>mf</sub>, to describe fluidization at low and high temperatures is discussed. Experimental u<sub>mb</sub>/u<sub>mf </sub>values obtained for the fresh FCC catalysts are compared with predictions.</p>

Role of Interparticle Forces in Development of Upper Plastic Limit of Clays

Nature ◽  
1961 ◽  
Vol 191 (4791) ◽  
pp. 938-939
Author(s):  
RAYMOND YONG ◽  
E. T. SELIG
Keyword(s):  
Plastic Limit ◽  
Interparticle Forces
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