scholarly journals Study of the conservation properties in two-way coupled dispersed multiphase flows using finite volume methods

2021 ◽  
Vol 2116 (1) ◽  
pp. 012071
Author(s):  
Linda Bahramian ◽  
Jordi Muela ◽  
C David Pérez-Segarra
Keyword(s):  
Carrier Phase ◽  
Multiphase Flows ◽  
Volume Fraction ◽  
Finite Volume Methods ◽  
Dispersed Phase ◽  
Volume Fractions ◽  
Large Eddy ◽  
Discrete Operators ◽  
Dispersed Phases ◽  
Dispersed Flows

Abstract In order to simulate dispersed multiphase flows, the coupling level must be determined according to the volume fraction in the system. The volume fraction is the ratio of the total volume of the dispersed phases over the total volume of the flow. In dilute flows, with volume fractions smaller than 10-6, only the influence of carrier phase over the dispersed phase is considered which is known as one-way coupling. Nonetheless, in dispersed flows with higher volume fractions, the effect of the dispersed phase over the continuous one should be taken into consideration, known as two-way coupling. This effect normally is applied as a source term in the conservation equations of the carrier phase. Depending on the numerical method and the discrete operators employed, these source terms can lead to some issues when aiming to preserve physical properties like mass, momentum and energy. Moreover, in order to validate the two-way coupling method, a particle-laden turbulent flow benchmark case with a mass loading of 22% is simulated by means of large eddy numerical simulation (LES). The aim of this work is to study the conservation properties of dispersed multiphase flows like momentum, kinetic energy and thermal energy through two-way coupling between dispersed and continuous phases.

scholarly journals In-Situ Continuous Monitoring of the Viscosity of Surfactant-Stabilized and Nanoparticles-Stabilized Pickering Emulsions

2019 ◽  
Vol 9 (19) ◽  
pp. 4044 ◽  
Author(s):  
Upinder Bains ◽  
Rajinder Pal
Keyword(s):  
Volume Fraction ◽  
Dispersed Phase ◽  
Pickering Emulsions ◽  
Volume Fractions ◽  
Shear Thinning Fluids ◽  
Oil In Water ◽  
Droplet Sizes ◽  
High Concentrations ◽  
The Stability

An in-situ method of measuring the viscosity of unstable and stable emulsions on a continuous basis under agitation conditions was developed and utilized to investigate the viscous behaviour of surfactant-stabilized and nanoparticles-stabilized oil-in-water (O/W) emulsions at different volume fractions of the dispersed phase (oil). The stability characteristics (droplet size and phase-separation) of emulsions under quiescent conditions were also determined with the aging of emulsions. Emulsions are Newtonian at low volume fractions of the dispersed phase. At high concentrations of the dispersed phase, emulsions behave as non-Newtonian shear-thinning fluids. The nanoparticles-stabilized (Pickering) emulsions are unstable in comparison with the surfactant-stabilized emulsions. The droplet sizes of Pickering emulsions increase rapidly with aging, whereas the droplet sizes of surfactant-stabilized remain nearly the same over a period of 24 h. However, Pickering emulsions are much more viscous than the surfactant-stabilized emulsions when comparison is made at the same volume fraction of the dispersed phase.

Proton radiography of explosively dispersed metal particles with varying volume fraction and varying carrier phase

Shock Waves ◽  
2021 ◽  
Author(s):  
K. T. Hughes ◽  
J. J. Charonko ◽  
K. P. Prestridge ◽  
N. H. Kim ◽  
R. T. Haftka ◽  
...  
Keyword(s):  
Carrier Phase ◽  
Volume Fraction ◽  
Metal Particles ◽  
Proton Radiography

scholarly journals An Intrinsic Material Tailoring Approach for Functionally Graded Axisymmetric Hollow Bodies Under Plane Elasticity

2021 ◽  
Author(s):  
Hassan Mohamed Abdelalim Abdalla ◽  
Daniele Casagrande
Keyword(s):  
Optimization Problem ◽  
Volume Fraction ◽  
Minimum Principle ◽  
Equivalent Stress ◽  
Micromechanical Model ◽  
Plane Elasticity ◽  
Functionally Graded ◽  
Pontryagin Minimum Principle ◽  
Volume Fractions ◽  
Material Tailoring

AbstractOne of the main requirements in the design of structures made of functionally graded materials is their best response when used in an actual environment. This optimum behaviour may be achieved by searching for the optimal variation of the mechanical and physical properties along which the material compositionally grades. In the works available in the literature, the solution of such an optimization problem usually is obtained by searching for the values of the so called heterogeneity factors (characterizing the expression of the property variations) such that an objective function is minimized. Results, however, do not necessarily guarantee realistic structures and may give rise to unfeasible volume fractions if mapped into a micromechanical model. This paper is motivated by the confidence that a more intrinsic optimization problem should a priori consist in the search for the constituents’ volume fractions rather than tuning parameters for prefixed classes of property variations. Obtaining a solution for such a class of problem requires tools borrowed from dynamic optimization theory. More precisely, herein the so-called Pontryagin Minimum Principle is used, which leads to unexpected results in terms of the derivative of constituents’ volume fractions, regardless of the involved micromechanical model. In particular, along this line of investigation, the optimization problem for axisymmetric bodies subject to internal pressure and for which plane elasticity holds is formulated and analytically solved. The material is assumed to be functionally graded in the radial direction and the goal is to find the gradation that minimizes the maximum equivalent stress. A numerical example on internally pressurized functionally graded cylinders is also performed. The corresponding solution is found to perform better than volume fraction profiles commonly employed in the literature.

scholarly journals A Micro-mechanical Investigation of Empirical Models for the Effective Properties of Aligned Short-Fibre Composites

1995 ◽  
Vol 4 (1) ◽  
pp. 096369359500400
Author(s):  
T.D. Papathanasiou
Keyword(s):  
Aspect Ratio ◽  
Volume Fraction ◽  
Tensile Modulus ◽  
Fibre Volume ◽  
Short Fibre ◽  
Computational Results ◽  
Volume Fractions ◽  
Fibre Composites ◽  
Effective Tensile Modulus ◽  
Fibre Aspect Ratio

The predictions of the Halpin equation concerning the effect of fibre volume fraction and fibre aspect ratio on the effective tensile modulus of uniaxially aligned short-fibre composites are compared with computational experiments on three-dimensional, multiparticle composite samples. The method of boundary elements is used to model the mechanical behaviour of composite specimens consisting of up to 40 discrete aligned fibres randomly dispersed in an elastic matrix. Statistical averages of computational results relating the effective tensile modulus to the aspect ratio and volume fraction of the fibres are found to agree very well with the predictions of the Halpin equation for fibre aspect ratio up to 10 and fibre volume fractions up to 20%. Computational results seem to indicate that the predictions of the Halpin equation fall bellow those of micro-mechanical models at higher volume fractions.

Prediction of liquid-liquid flow in an SMX static mixer using large eddy simulations

2010 ◽  
Vol 64 (2) ◽  
Author(s):  
Paulina Pianko-Oprych ◽  
Zdzisław Jaworski
Keyword(s):  
Centrifugal Force ◽  
Liquid Flow ◽  
Concentration Distribution ◽  
Large Eddy Simulations ◽  
Dispersed Phase ◽  
Static Mixer ◽  
Phase Concentration ◽  
Large Eddy ◽  
Smx Static Mixer ◽  
The Impact

AbstractThe main purpose of the paper is to apply the large eddy simulations (LES) technique and to verify its use as a predicting tool for turbulent liquid-liquid flow in an SMX static mixer. LES modeling was carried out using the Smagorinsky-Lilly model of the turbulent subgrid viscosity for the Reynolds number of 5000 and 10000. The continuous phase was water and the dispersed phase was silicon oil. The investigation covers the effects of the density ratio between the phases. Three different cases of liquid densities were considered. The dispersed phase concentration distribution in the mixer cross-sections was compared with the corresponding time averaged results obtained formerly for the same configuration in a steady-state simulation using the standard RANS approach with the k-ɛ model. The dependency of the standard deviation of the dispersed phase concentration on the distance from the mixer inlet and the impact of the centrifugal force on the phase concentration distribution were investigated. The presented results for the SMX static mixer confirm conclusions of previous studies by Jaworski et al. (2006) obtained for a Kenics static mixer and show less a pronounced influence of the centrifugal force on the phase concentration distribution of the LES results in comparison to the RANS case.

Variant Selection in Zr Alloys: How Many Variants Generated from one Beta Grain?

2005 ◽  
Vol 105 ◽  
pp. 133-138 ◽  
Author(s):  
Pierre Barbéris ◽  
Frank Montheillet ◽  
Cédric Chauvy
Keyword(s):  
Elastic Energy ◽  
Volume Fraction ◽  
Variant Selection ◽  
Energy Minimum ◽  
Maximum Volume ◽  
Volume Fractions ◽  
Minimum Number ◽  
Simplifying Assumptions ◽  
Maximum Volume Fraction ◽  
Zr Alloys

The elastic energy of a set of the twelve variants generated during the b ® a transformation of zirconium, with volume fractions fi, i=1..12, is derived with simplifying assumptions and the conditions on the fi to reach the energy minimum are established analytically. The minimum number of variants needed to reach this minimum is shown to be 6, and in this case, the variants have very specific volume fractions. Another result is that the maximum volume fraction of any variant is 1/3.

The Influence of Multiple Inclusions on the Cauchy Stress of a Spherical Particle-Reinforced Composite Under Uniaxial Loading

2014 ◽  
Author(s):  
Ke Niu ◽  
Armin Abedini ◽  
Zengtao Chen
Keyword(s):  
Spherical Particle ◽  
Single Particle ◽  
Volume Fraction ◽  
Unit Cell ◽  
Spherical Particles ◽  
Uniaxial Tensile ◽  
Cauchy Stress ◽  
Particle Volume ◽  
Volume Fractions ◽  
Unit Cells

This paper investigates the influence of multiple inclusions on the Cauchy stress of a spherical particle-reinforced metal matrix composite (MMC) under uniaxial tensile loading condition. The approach of three-dimensional cubic multi-particle unit cell is used to investigate the 15 non-overlapping identical spherical particles which are randomly distributed in the unit cell. The coordinates of the center of each particle are calculated by using the Random Sequential Adsorption algorithm (RSA) to ensure its periodicity. The models with reinforcement volume fractions of 10%, 15%, 20% and 25% are evaluated by using the finite element method. The behaviour of Cauchy stress for each model is analyzed at a far-field strain of 5%. For each reinforcement volume fraction, four models with different particle spatial distributions are evaluated and averaged to achieve a more accurate result. At the same time, single-particle unit cell and analytical model were developed. The stress-strain curves of multi-particle unit cells are compared with single-particle unit cells and the tangent homogenization model coupled with the Mori-Tanaka method. Only little scatters were found between unit cells with the same particle volume fractions. Multi-particle unit cells predict higher response than single particle unit cells. As the volume fraction of reinforcements increases, the Cauchy stress of MMCs increases.

Performance of Bamboo Fiber Reinforced Composites: Mechanical Properties

2021 ◽  
Vol 879 ◽  
pp. 284-293
Author(s):  
Norliana Bakar ◽  
Siew Choo Chin
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Vinyl Ester ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Bamboo Fiber ◽  
Synthetic Fiber ◽  
Fiber Reinforced ◽  
Fiber Volume ◽  
Volume Fractions

Fiber Reinforced Polymer (FRP) made from synthetic fiber had been widely used for strengthening of reinforced concrete (RC) structures in the past decades. Due to its high cost, detrimental to the environment and human health, natural fiber composites becoming the current alternatives towards a green and environmental friendly material. This paper presents an investigation on the mechanical properties of bamboo fiber reinforced composite (BFRC) with different types of resins. The BFRC specimens were prepared by hand lay-up method using epoxy and vinyl-ester resins. Bamboo fiber volume fractions, 30%, 35%, 40%, 45% and 50% was experimentally investigated by conducting tensile and flexural test, respectively. Results showed that the tensile and flexural strength of bamboo fiber reinforced epoxy composite (BFREC) was 63.2% greater than the bamboo fiber reinforced vinyl-ester composite (BFRVC). It was found that 45% of bamboo fiber volume fraction on BFREC exhibited the highest tensile strength compared to other BFRECs. Meanwhile, 40% bamboo fiber volume fraction of BFRVC showed the highest tensile strength between bamboo fiber volume fractions for BFRC using vinyl-ester resin. Studies showed that epoxy-based BFRC exhibited excellent results compared to the vinyl-ester-based composite. Further studies are required on using BFRC epoxy-based composite in various structural applications and strengthening purposes.

scholarly journals Simulation of the Effect of Oil Volume Fractions in an Oil-Water Flows Along a Circular Pipe: A Finite Element Approach

2018 ◽  
Vol 10 (5) ◽  
pp. 19
Author(s):  
Ferdusee Akter ◽  
Md. Bhuyan ◽  
Ujjwal Deb
Keyword(s):  
Finite Element ◽  
Volume Fraction ◽  
Fluid Velocity ◽  
Galerkin Approximation ◽  
Computational Domain ◽  
Two Phase Flows ◽  
Two Phase ◽  
Volume Fractions ◽  
Oil In Water ◽  
Element Approach

Two phase flows in pipelines are very common in industries for the oil transportations. The aim of our work is to observe the effect of oil volume fraction in the oil in water two phase flows. The study has been accomplished using a computational model which is based on a Finite Element Method (FEM) named Galerkin approximation. The velocity profiles and volume fractions are performed by numerical simulations and we have considered the COMSOL Multiphysics Software version 4.2a for our simulation. The computational domain is 8m in length and 0.05m in radius. The results show that the velocity of the mixture decreases as the oil volume fraction increases. It should be noted that if we gradually increase the volume fractions of oil, the fluid velocity also changes and the saturated level of the volume fraction is 22.3%.

scholarly journals An experimental evaluation of the solute transport volume in biodegraded municipal solid waste

1999 ◽  
Vol 3 (3) ◽  
pp. 429-438 ◽  
Author(s):  
H. Rosqvist ◽  
D. Bendz
Keyword(s):  
Solute Transport ◽  
Solid Waste ◽  
Volume Fraction ◽  
Tracer Tests ◽  
Travel Times ◽  
Volume Fractions ◽  
Rapid Flow ◽  
Set Up ◽  
Log Normal ◽  
Transport Volume

Abstract. A large undisturbed sample (3.5 m3) of 22-year-old, biodegraded solid waste set up to estimate the volume fraction participating in the transport of solutes through the waste material. Altogether, five tracer tests were performed under ponding and sprinkling conditions, and under steady-state and transient conditions. The experimental break through curves (BTCs), which indicated a non-equilibrium transport of the solute by early peaks and long right-hand tails, were used to parameterize log-normal solute travel time probability density functions. The expected solute travel times (i.e. the median solute travel times) were assessed and the corresponding fraction of the experimental volumes active in the transport of solutes was estimated. The solute transport volume fractions defined by the median solute travel times were estimated to vary between 5 and 10% of the total experimental volume. Further, the magnitudes of the solute transport volume fractions defined by the modal (peak) solute travel times were estimated to vary between 1 and 2% of the total experimental volume. In addition, possible boundary effects in terms of rapid flow along the wall of the experimental column were investigated.

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