scholarly journals A discrete model for the apparent viscosity of polydisperse suspensions including maximum packing fraction

2013 ◽  
Vol 57 (3) ◽  
pp. 743-765 ◽  
Author(s):  
Aaron Dörr ◽  
Amsini Sadiki ◽  
Amirfarhang Mehdizadeh
Keyword(s):  
Apparent Viscosity ◽  
Discrete Model ◽  
Packing Fraction ◽  
Maximum Packing Fraction

Yield stress and maximum packing fraction of concentrated suspensions

1995 ◽  
Vol 34 (6) ◽  
pp. 544-561 ◽  
Author(s):  
James Z. Q. Zhou ◽  
Peter H. T. Uhlherr ◽  
Fang Tunan Luo
Keyword(s):  
Yield Stress ◽  
Packing Fraction ◽  
Concentrated Suspensions ◽  
Maximum Packing Fraction

Investigation on maximum packing fraction of bitumen particles during emulsion drying

2021 ◽  
Vol 54 (5) ◽  
Author(s):  
Jian Ouyang ◽  
Peng Cao ◽  
Taixiong Tang ◽  
Yan Meng
Keyword(s):  
Packing Fraction ◽  
Maximum Packing Fraction

scholarly journals A new empirical viscosity model for composed suspensions used in experiments of sediment gravity flows

RBRH ◽  
2021 ◽  
Vol 26 ◽  
Author(s):  
Camila Castro ◽  
Ana Luiza de Oliveira Borges ◽  
Rafael Manica
Keyword(s):  
Physical Simulation ◽  
Relative Viscosity ◽  
Packing Fraction ◽  
Turbidity Currents ◽  
Single Model ◽  
Gravitational Flow ◽  
Sediment Gravity Flows ◽  
Gravity Flows ◽  
Clay Percentage ◽  
Maximum Packing Fraction

ABSTRACT Sediment gravity flows are natural flows composed by water and sediment in which the gravitational flow acts on the sediment. The distinct physical properties of the cohesive (clay) and non-cohesive (sand) sediment, and the interaction between these particles alter the ability of the flow to resist to the movement (rheology) along time and space, represented by the viscosity of a mixture suspension. Hence, we propose to study the rheological properties of those mixtures and calculate their relative viscosity when used in the physical simulation of turbidity currents. Rheological tests were performed with various mixtures composed by water, clay and/or coal. Two equations are proposed to estimate the relative viscosity as a function of volume concentration of each sediment, the maximum packing fraction and the percentage of clay present in the mixture. The results also show an error close to 20% comparing similar models from the literature, which are satisfactory. The results also demonstrate that caution should be exercised when generalizing the use of a single model to predict the relative viscosity of suspensions. The influence of density (ρ), grain shape, clay percentage (Cclay), volumetric concentration (ϕ) and maximum packaging fraction (ϕmax) should be considered in the formulation of the equations.

scholarly journals Stiffening Effect of Fillers Based on Rheology and Micromechanics Models

2021 ◽  
Vol 11 (14) ◽  
pp. 6521
Author(s):  
Abdur Rahim ◽  
Abdalrhman Milad ◽  
Nur Izzi Md Yusoff ◽  
Gordon Airey ◽  
Nick Thom
Keyword(s):  
Asphalt Mixture ◽  
Packing Fraction ◽  
Effective Volume ◽  
Master Curves ◽  
Micromechanics Models ◽  
Different Temperatures ◽  
Linear Viscoelastic ◽  
Maximum Packing Fraction ◽  
Stiffening Effect ◽  
Good Agreement

The aggregate in an asphalt mixture is coated with mastic consisting of bitumen (dilute phase) and filler (particulates phase). The interaction of bitumen and filler and packing of filler plays an important role in the properties of mastics. The micromechanics models from composite rheology can be used to predict the stiffening effect of a suspension. In this research, the stiffening effect of fillers was investigated based on the rheology of mastic. The frequency sweep tests in a dynamic shear rheometer at different temperatures were performed within a linear viscoelastic range to construct the master curves. The volume fractions were expressed as compositional volumes of filler in mastic. The particle shape and surface texture are determined through microscopy. We used six micromechanics-based models to predict the stiffening potential of fillers in mastics. The models include Maron–Pierce, Lewis Nielsen, Mooney, Krieger–Dougherty, Chong, Robinson, and Hashin Models. The results show that the same volume content of filler has a different effective volume. The fillers increase the stiffening effect of the composite, especially at high temperatures. The behaviour of fillers with similar effective volume and packing is identical. The filler type affects the stiffening of mastics. Micromechanics modelling results show that most models show an accurate stiffening effect at lower concentrations with the exception of the Chong Model. The Maron–Pierce Model under-estimates the stiffening potential for granite mastic at higher concentrations beyond the 30% filler content fraction. The value of maximum packing fraction (ϕm) and Einstien coefficient (KE) in the Mooney model are significantly different from other models for limestone and granite, respectively. The line of equality graph shows good agreement of measured and predicted stiffness. It is difficult to precisely model the mastic data with any single model due to the presence of complex stiffening effects beyond volume filling.

scholarly journals Calculation of Dynamic Viscosity in Concentrated Cementitious Suspensions: Probabilistic Approximation and Bayesian Analysis

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1971
Author(s):  
Ángel De La Rosa ◽  
Gonzalo Ruiz ◽  
Enrique Castillo ◽  
Rodrigo Moreno
Keyword(s):  
Bayesian Analysis ◽  
Dynamic Viscosity ◽  
Probabilistic Models ◽  
Packing Fraction ◽  
Point Of View ◽  
Deterministic Models ◽  
Cement Pastes ◽  
Random Nature ◽  
Probabilistic Point ◽  
Maximum Packing Fraction

We present a new focus for the Krieger–Dougherty equation from a probabilistic point of view. This equation allows the calculation of dynamic viscosity in suspensions of various types, like cement paste and self-compacting mortar/concrete. The physical meaning of the parameters that intervene in the equation (maximum packing fraction of particles and intrinsic viscosity), together with the random nature associated with these systems, make the application of the Bayesian analysis desirable. This analysis permits the transformation of parametric-deterministic models into parametric-probabilistic models, which improves and enriches their results. The initial limitations of the Bayesian methods, due to their complexity, have been overcome by numerical methods (Markov Chain Monte Carlo and Gibbs Sampling) and the development of specific software (OpenBUGS). Here we use it to compute the probability density functions that intervene in the Krieger–Dougherty equation applied to the calculation of viscosity in several cement pastes, self-compacting mortars, and self-compacting concretes. The dynamic viscosity calculations made with the Bayesian distributions are significantly better than those made with the theoretical values.

scholarly journals Filling of Irregular Channels with Round Cross-Section: Modeling Aspects to Study the Properties of Porous Materials

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1901 ◽  
Author(s):  
Yamel Ungson ◽  
Larysa Burtseva ◽  
Edwin Garcia-Curiel ◽  
Benjamin Valdez Salas ◽  
Brenda Flores-Rios ◽  
...  
Keyword(s):  
Cross Section ◽  
Circular Cross Section ◽  
Packing Fraction ◽  
Close Packing ◽  
Porous Structures ◽  
Round Cross Section ◽  
Packing Factor ◽  
First Approximation ◽  
Maximum Packing Fraction ◽  
Round Cross

The filling of channels in porous media with particles of a material can be interpreted in a first approximation as a packing of spheres in cylindrical recipients. Numerous studies on micro- and nanoscopic scales show that they are, as a rule, not ideal cylinders. In this paper, the channels, which have an irregular shape and a circular cross-section, as well as the packing algorithms are investigated. Five patterns of channel shapes are detected to represent any irregular porous structures. A novel heuristic packing algorithm for monosized spheres and different irregularities is proposed. It begins with an initial configuration based on an fcc unit cell and the subsequent densification of the obtained structure by shaking and gravity procedures. A verification of the algorithm was carried out for nine sinusoidal axisymmetric channels with different Dmin/Dmax ratio by MATLAB® simulations, reaching a packing fraction of at least 0.67 (for sphere diameters of 5%Dmin or less), superior to a random close packing density. The maximum packing fraction was 73.01% for a channel with a ratio of Dmin/Dmax = 0.1 and a sphere size of 5%Dmin. For sphere diameters of 50%Dmin or larger, it was possible to increase the packing factor after applying shaking and gravity movements.

The effects of an addition of force-free particles on the rheological properties of fine suspensions

1995 ◽  
Vol 32 (2) ◽  
pp. 263-270 ◽  
Author(s):  
Philippe Coussot ◽  
Jean-Michel Piau
Keyword(s):  
Shear Rate ◽  
Yield Stress ◽  
Packing Fraction ◽  
Solid Concentration ◽  
Power Parameter ◽  
Rate Range ◽  
Water Suspensions ◽  
Rate Of Increase ◽  
Free Particles ◽  
Maximum Packing Fraction

This study provides some elements for understanding the behavior of water–debris mixtures containing clay, silt, sand, and boulders at high solid concentrations. Accurate, simple shear rheometrical results for various clay–water mixtures and fine debris flow fractions with different added sand concentrations, in the shear rate range from 10−2 to 10−2 s−1 are presented. In this shear rate range, the behavior of these fluids is similar to the behavior of the initial fluid (without sand), i.e., it may be well represented by a Herschel–Bulkley model (with a power parameter close to 1/3). With the initial fluids (yield stress from 20 to 200 Pa) the suspension yield stress increases exponentially with the increase in sand (diameter between 100 and 200 μm) concentration, as long as the latter does not exceed 30%. However the rate of increase is less than the corresponding rate for the initial fluid and is correspondingly smaller as the grain size distribution is less well sorted. Diagrams showing the increase of yield stress with solid concentration may help to estimate the yield stress of coarser suspensions as long as the solid fraction is not too close to the maximum packing fraction. Key words : clay–water suspensions, water–debris mixtures, rheology, yield stress, sand addition, rheometry.

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