Concentrated emulsions. Investigation of polydispersity and droplet distortion and their effect on volume fraction and interfacial area

Langmuir ◽  
1990 ◽  
Vol 6 (11) ◽  
pp. 1668-1675 ◽  
Author(s):  
Ashok K. Das ◽  
Pushpito K. Ghosh
Keyword(s):  
Volume Fraction ◽  
Interfacial Area ◽  
Concentrated Emulsions

Fiber-Matrix Interfacial Area Reduction in Fiber Reinforced Cements and Concretes at Moderate to High Fiber Volume Fractions

1994 ◽  
Vol 370 ◽  
Author(s):  
Gebran N. Karam
Keyword(s):  
Mechanical Properties ◽  
Volume Fraction ◽  
Interfacial Area ◽  
Composite Fiber ◽  
Short Fiber ◽  
Published Data ◽  
Fiber Reinforced ◽  
Fiber Volume ◽  
High Fiber ◽  
Fiber Matrix

AbstractThe area and properties of the fiber-matrix interface in fiber reinforced cements and concretes determines the amount of stress transferred forth and back between the cement paste and the reinforcement and hence controls the mechanical properties of the composite. Fiber-fiber interaction and overlap of fibers with fibers, voids and aggregates can dramatically decrease the efficiency of the reinforcement by reducing this interfacial area. A simple model to account for this reduction is proposed and ways to integrate it in the models describing the mechanical properties of short fiber reinforced concretes are presented. The parameters of the model are evaluated from previously published data sets and its predictions are found to compare well with experimental observations; for example, it is able to predict the non-linear variation of bending and tensile strength with increasing fiber volume fraction as well as the existence of an optimal fiber content.

Effect of Carbon Black on Hysteresis of Rubber Vulcanizates: Equivalence of Surface Area and Loading

1976 ◽  
Vol 49 (4) ◽  
pp. 1076-1094 ◽  
Author(s):  
J. M. Caruthers ◽  
R. E. Cohen ◽  
A. I. Medalia
Keyword(s):  
Carbon Black ◽  
Surface Area ◽  
Functional Form ◽  
Volume Fraction ◽  
Dynamic Properties ◽  
Dynamic Test ◽  
Practical Interest ◽  
Interfacial Area ◽  
Experimental Conditions ◽  
Tan Δ

Abstract We have developed an empirical correlation between the loss tangent (tan δ) and the product of the volume fraction (ϕ) of carbon black in the composite and the total filler-polymer interfacial area per unit volume of composite (ψ). This correlation was applied to vulcanizates based on SBR-1500, SBR-1712, and NR with various compounding procedures and under different deformation conditions, including forced vibration nonresonant dynamic test machines, and the Goodyear-Healey pendulum rebound. The functional form of the correlation was qualitatively similar in all instances ; however, quantitative aspects of the correlation are dependent upon the particular experimental conditions. Tan δ is a weak function of the deformation amplitude over the region of practical interest. This is in contrast to hysteretic energy loss, which is proportional to the square of the amplitude. The validity of the correlation over wide ranges of amplitude, temperature, and frequency indicates that the viscoelastic relaxation or loss processes are similar over the range of conditions studied. Since the combined parameter, ϕψ, is proportional to ϕ2 multiplied by the specific surface area of the carbon black, this relation implies an equivalence between surface area and loading, with regard to tan 5. It has previously been shown that the elastic modulus depends on structure and loading. Thus, the dynamic properties, including hysteresis under various conditions, can be predicted from the carbon black properties, and compounds can be designed for desired dynamic properties by independent adjustment of loading, structure and surface area.

Influence of Cluster Formation: Viscosity of Concentrated Emulsions

2003 ◽  
Vol 13 (5) ◽  
pp. 259-264 ◽  
Author(s):  
G. Kyazze ◽  
V. Starov
Keyword(s):  
Experimental Data ◽  
Shear Rate ◽  
Volume Fraction ◽  
Cluster Formation ◽  
Relative Viscosity ◽  
Skim Milk ◽  
Colloid Interface ◽  
Rate Range ◽  
Concentrated Emulsions ◽  
Fraction Comparison

Abstract Recently a new theory of viscosity of concentrated emulsions dependency on volume fraction of droplets (Starov V, Zhdanov G: J. Colloid Interface Sci, 258, 404 (2003)) has been suggested that relates the viscosity of concentrated emulsions to formation of clusters. Through experiments with milk at different concentrations of fat, cluster formation has been validated using optical microscopy and their properties determined using the mentioned theory. Viscometric studies have shown that within the shear rate range studied, both the packing density of fat droplets inside clusters and the relative viscosity of milk (viscosity over skim milk viscosity) are independent of shear-rate, but vary with volume fraction. Comparison of the experimental data with previous theories that assumed that the particles remained discrete shows wide variation. We attribute the discrepancy to cluster formation.

scholarly journals Volume of Fluid Computations of Gas Entrainment and Void Fraction for Plunging Liquid Jets to Aerate Wastewater

2020 ◽  
Vol 4 (4) ◽  
pp. 56
Author(s):  
Ali Bahadar
Keyword(s):  
Void Fraction ◽  
Volume Fraction ◽  
Piecewise Linear ◽  
Industrial Effluents ◽  
Air Entrainment ◽  
Interfacial Area ◽  
Volume Of Fluid ◽  
Liquid Jets ◽  
Entrainment Rate ◽  
Entrained Air

Among various mechanisms for enhancing the interfacial area between gases and liquids, a vertical liquid jet striking a still liquid is considered an effective method. This method has vast industrial and environmental applications, where a significant application of this method is to aerate industrial effluents and wastewater treatment. Despite the huge interest and experimental and numerical efforts made by the academic and scientific community in this topic, there is still a need of further study to realize improved theoretical and computational schemes to narrow the gap between the measured and the computed entrained air. The present study is a numerical attempt to highlight the air being entrained by water jet when it intrudes into a still water surface in a tank by the application of a Volume of Fluid (VOF) scheme. The VOF scheme, along with a piecewise linear interface construction (PLIC) algorithm, is useful to follow the interface of the air and water bubbly plume and thus can provide an estimate of the volume fraction for the gas and the liquid. Dimensionless scaling derived from the Fronde number and Reynolds number along with geometric similarities due to the liquid jet’s length and nozzle diameter have been incorporated to validate the experimental data on air entrainment, penetration and void fraction. The VOF simulations for void fraction and air-water mixing and air jet’s penetration into the water were found more comparable to the measured values than those obtained using empirical and Euler-Euler methods. Although, small overestimates of air entrainment rate compared to the experiments have been found, however, VOF was found effective in reducing the gap between measurements and simulations.

Numerical Simulation of Droplet Flows and Evaluation of Interfacial Area

2002 ◽  
Vol 124 (3) ◽  
pp. 576-583 ◽  
Author(s):  
T. Watanabe ◽  
K. Ebihara
Keyword(s):  
Lattice Boltzmann ◽  
Weber Number ◽  
Volume Fraction ◽  
Interfacial Area ◽  
Force Balance ◽  
Two Phase ◽  
Critical Weber Number ◽  
Boltzmann Method ◽  
Droplet Flows ◽  
Good Agreement

Droplet flows with coalescence and breakup are simulated numerically using the lattice Boltzmann method. It is shown that the rising velocities are in good agreement with those obtained by the force balance and the empirical correlation. The breakup of droplets after coalescence is simulated well in terms of the critical Weber number. A numerical method to evaluate the interfacial area and the volume fraction in two-phase flows is proposed. It is shown that the interfacial area corresponds to the shape, the number and the size of droplets, and the proposed method is effective for numerical evaluation of interfacial area even if the interface changes dynamically.

Interfacial Area and Number Density Transport Equations for Modeling Multiphase Flows With Cavitation

2005 ◽  
Author(s):  
De Ming Wang ◽  
Jaehoon Han ◽  
David Greif ◽  
Iztok Zun ◽  
Matjaz Perpar
Keyword(s):  
Cavitation Erosion ◽  
Volume Fraction ◽  
Interfacial Area ◽  
Physical Models ◽  
Number Density ◽  
Cavitating Flows ◽  
Bubble Distribution ◽  
Bubble Breakup ◽  
Bubble Number ◽  
Bubble Number Density

In this paper we report progress toward developing advanced cavitation models with Eulerian multifluid method. The bubble number density and the interfacial area equations are introduced into the general framework of multifluid method for multiphase cavitating flows in order to account for the variable size nature of the bubble distribution. The physical models for bubble breakup and coalescence are based on the work by Ishii group’s work in recent years. Simulation results of a cavitating flow are compared with the corresponding experimental data, which include the bubble size distribution, bubble volume fraction and bubble number density. The ability of predicting bubble distribution characteristics is particularly useful as an input for cavitation erosion analysis.

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