scholarly journals Rheology of concentrated suspensions of non-colloidal rigid fibres

2017 ◽  
Vol 827 ◽  
Author(s):  
Franco Tapia ◽  
Saif Shaikh ◽  
Jason E. Butler ◽  
Olivier Pouliquen ◽  
Élisabeth Guazzelli
Keyword(s):  
Friction Coefficient ◽  
Aspect Ratio ◽  
Volume Fraction ◽  
Normal Stresses ◽  
Maximum Volume ◽  
Concentrated Suspensions ◽  
Suspension Flows ◽  
Jamming Transition ◽  
Aspect Ratios ◽  
Maximum Volume Fraction

Pressure- and volume-imposed rheology is used to study suspensions of non-colloidal, rigid fibres in the concentrated regime for aspect ratios ranging from 3 to 15. The suspensions exhibit yield stresses. Subtracting these apparent yield stresses reveals a viscous scaling for both the shear and normal stresses. The variation in aspect ratio does not affect the friction coefficient (ratio of shear and normal stresses), but increasing the aspect ratio lowers the maximum volume fraction at which the suspension flows. Constitutive laws are proposed for the viscosities and the friction coefficient close to the jamming transition.

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.

Heatline and Massline Visualization of Hydromagnetic Double Diffusive Convective Flow of Nanofluid Within a Porous Trapezoidal Cavity

2021 ◽  
Vol 10 (2) ◽  
pp. 270-284
Author(s):  
Bikash C. Saha ◽  
T. R. Mahapatra ◽  
Dulal Pal
Keyword(s):  
Aspect Ratio ◽  
Convective Flow ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Darcy Number ◽  
Temperature Fields ◽  
Computational Domain ◽  
Aspect Ratios ◽  
Numerical Predictions ◽  
Double Diffusive

Double diffusive convective flow of nanofluid within a porous trapezoidal cavity of various aspect ratios consisting of Al2O3 nanoparticle in the presence of applied magnetic field in the direction perpendicular to the parallel top and bottom walls is analysed. The side walls of the cavity are maintained at constant temperature and concentration while its horizontal walls are insulated and impermeable. The irregular physical domain of the problem is transformed to a regular unit square computational domain. The governing equations have been solved by second order of finite difference method (FDM). Based upon numerical predictions, the effects of pertinent parameters such as Rayleigh number, Darcy number, aspect ratio, solid volume fraction and inclination angle on the flow and temperature fields and the heat transfer performance of the enclosure are examined. It is found that the intensity of heat and mass transfer increases with the increase in the Darcy number and aspect ratio. It is also observed that as the solid volume fraction increases there is increase in the average Nusselt number but reverse effect is observed on the average Sherwood number.

scholarly journals Effects of circular corners and aspect-ratio on entropy generation due to natural convection of nanofluid flows in rectangular cavities

2015 ◽  
Vol 19 (5) ◽  
pp. 1621-1632 ◽  
Author(s):  
Mahmoud Salari ◽  
Ali Mohammadtabar ◽  
Mohammad Mohammadtabar
Keyword(s):  
Natural Convection ◽  
Rayleigh Number ◽  
Aspect Ratio ◽  
Entropy Generation ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Bejan Number ◽  
Total Entropy ◽  
Aspect Ratios ◽  
Corner Radius

In this paper, entropy generation induced by natural convection of cu-water nanofluid in rectangular cavities with different circular corners and different aspect-ratios were numerically investigated. The governing equations were solved using a finite volume approach and the SIMPLE algorithm was used to couple the pressure and velocity fields. The results showed that the total entropy generation increased with the increase of Rayleigh number, irreversibility coefficient, aspect ratio or solid volume fraction while it decreased with the increase of the corner radius. It should be noted that the best way for minimizing entropy generation is decreasing Rayleigh number. This is the first priority for minimizing entropy generation. The other parameters such as radius, volume fraction, etc are placed on the second priority. However, Bejan number had an inverse trend compared with total entropy generation. As an exception, Bejan number and total entropy number had the same trend whenever solid volume fraction increased. Moreover, Nusselt number increased as Rayleigh number, solid volume fraction or aspect ratio increased whereas it decreases with the increase of corner radius.

Cement Viscosity As A Function Of Concentration

1992 ◽  
Vol 289 ◽  
Author(s):  
Leslie J. Struble ◽  
Guo-Kuang Sun
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Portland Cement ◽  
Volume Fraction ◽  
Optimization Techniques ◽  
Viscosity Data ◽  
Maximum Volume ◽  
Cement Pastes ◽  
Maximum Volume Fraction ◽  
Measured Viscosity

AbstractThe Krieger-Dougherty equation allows calculation of viscosity as a function of volume fraction for suspensions of noninteracting particles. For model suspensions (of spherical, monosized particles), it has been shown to provide excellent agreement between calculated and measured viscosities. In the present study, this equation was applied to portland cement pastes, also with good correlations between calculated and measured viscosities. Because cement has a broad particle size distribution and its particles are angular and elongated, the two constants in this equation (the maximum volume fraction and the intrinsic viscosity) were estimated using nonlinear optimization techniques. The equation provides an excellent fit to measured viscosity data. However, the nature of the equation makes the estimation somewhat difficult, and the solutions are not well-defined.

Can the maximum volume fraction ensure optimum reinforcement in short‐fiber composites?

2019 ◽  
Vol 136 (31) ◽  
pp. 47821
Author(s):  
Florencia Cruces ◽  
María Guadalupe García ◽  
Nelio Ariel Ochoa
Keyword(s):  
Volume Fraction ◽  
Fiber Composites ◽  
Short Fiber ◽  
Maximum Volume ◽  
Optimum Reinforcement ◽  
Maximum Volume Fraction

The Effect of Nano SiO2 Particle Size Distribution on Rheological Behaviour of Shear Thickening Fluids

2013 ◽  
Vol 58 (4) ◽  
pp. 1323-1326 ◽  
Author(s):  
A. Idźkowska ◽  
M. Szafran
Keyword(s):  
Particle Size ◽  
Shear Rate ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Volume Fraction ◽  
Ceramic Powder ◽  
Shear Thickening ◽  
Measuring System ◽  
Maximum Volume ◽  
Maximum Volume Fraction

Abstract In present work the influence of particle size distribution on the dilatant effect of shear thickening fluid was investigated. As a ceramic powder a mixture of silicas 200 and 7 nm in ratio 95:5, 90:10, 85:15, 80:20, 75:25, 50:50 was used. A dispersing agent was poly (propylene glycol) of a molecular weight of 425 g/mol. The as prepared slurries were examined on a rotational rheometer Kinexus Pro with a plate-plate measuring system at room temperature, where the viscosity as a function of shear rate was investigated. The measurement showed that by partially replacing greater particle size by smaller one, it is possible to shift the onset of shear thickening to the higher value of shear rate, however, the decreases of dilatant effect is observed. The influence of particle size distribution on a maximum volume fraction also was investigated. The maximum volume fraction which was passible to obtain was 35 vol%.

Study of Retained Austenite in Q&P Steel for Automobile

2012 ◽  
Vol 482-484 ◽  
pp. 1436-1441 ◽  
Author(s):  
Bao Tong Zhuang ◽  
Hai Tao Jiang ◽  
Di Tang ◽  
Zhen Li Mi ◽  
Zhen Kuai
Keyword(s):  
Grain Boundaries ◽  
Retained Austenite ◽  
Volume Fraction ◽  
Carbon Partitioning ◽  
Maximum Volume ◽  
Quenching And Partitioning ◽  
Maximum Volume Fraction ◽  
Intercritical Region

Retained austenite of Q&P (Quenching and Partitioning) processed 0.2C-1.51Si-1.84Mn steel heated in intercritical region and full austenite region are investigated. The results show that the maximum volume fraction of retained austenite heated in intercritical and full austenite region is 13.39% and 5.23% respectively. Carbon partitioning completed within 10 s for both heating modes. The microstructure after full austenitization consisted of martensite laths and thin, inter-lath retained austenite film. Austenite blocks is observed as well after partial austenitization.The distribution of retained austenite is related to the amount of grain boundaries by EBSD techniques.

Experimental study of the sedimentation of dilute and semi-dilute suspensions of fibres

1999 ◽  
Vol 384 ◽  
pp. 133-158 ◽  
Author(s):  
BENJAMIN HERZHAFT ◽  
ÉLISABETH GUAZZELLI
Keyword(s):  
Aspect Ratio ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Complex Function ◽  
Orientation Distribution ◽  
Particle Volume ◽  
Mean Velocity ◽  
Aspect Ratios ◽  
Dilute Suspensions ◽  
Orientation Distributions

Steady-state velocity and orientation distributions of sedimenting fibres were measured as a function of particle concentration and aspect ratio. Two different regimes of sedimentation were clearly identified. For dilute suspensions, the fibres tend to align in the direction of gravity with occasional flipping and clump together to form packets. In this regime, the vertical mean sedimentation speed is not hindered and can be larger than the Stokes' velocity of an isolated vertical fibre. Its scaling is a complex function of particle volume fraction and aspect ratio. As the concentration is increased, the fibres still tend to orient in the direction of gravity. The mean velocity becomes hindered and scales with particle volume fraction. The velocity fluctuations were found to be large and anisotropic. They were found to increase with increasing volume fraction. A similar substantial anisotropy of the orientation distribution was observed for all particle concentrations and aspect ratios studied.

scholarly journals Hybrid Effect of Twisted Steel and Polyethylene Fibers on the Tensile Performance of Ultra-High-Performance Cementitious Composites

Polymers ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 879 ◽  
Author(s):  
Min-Jae Kim ◽  
Soonho Kim ◽  
Doo-Yeol Yoo
Keyword(s):  
Tensile Strength ◽  
Aspect Ratio ◽  
High Performance ◽  
Performance Test ◽  
Volume Fraction ◽  
Synergetic Effect ◽  
Hybrid Effect ◽  
Strain Capacity ◽  
Aspect Ratios ◽  
Tensile Performance

The hybrid effect of twisted steel (T) fibers with an aspect ratio of 100 and polyethylene (PE) fibers with four different aspect ratios of 400, 600, 900, and 1200 on the mechanical performance of ultra-high-performance cementitious composite (UHPCC) was investigated. This involved a total of 17 different sample types at an identical fiber volume fraction of 2% being made and subjected to compressive and tensile loads. Samples were made by replacing 0.5%, 1.0%, 1.5%, and 2.0% of T fibers with four different types of PE fibers. In addition, the pullout behaviors of fibers at cracked sections and the cracking behaviors of specimens were evaluated in order to determine the effect of the pullout mechanism of each fiber on the overall tensile performance. Test results indicate that the compressive strength decreased in proportion to the amount of PE fibers, regardless of their aspect ratio. The fiber hybridization had a great synergetic effect, successfully improving the tensile strength and strain capacity of UHPCCs; this effect was dependent on the aspect ratio of the PE fibers. Finally, the cracking behaviors were determined to be more related to the fiber type and pullout mechanisms than the tensile strength or strain capacity of UHPCCs.

scholarly journals STUDY OF THREE DIMENSIONAL LAMINAR FORCED CONVECTION OF NANO FLUID FLOW THROUGH ECCENTRIC RECTANGULAR ANNULAR DUCT

2018 ◽  
Vol 22 ◽  
pp. 01042
Author(s):  
Amr G. Eltorky ◽  
Mohamed Elhelw ◽  
Mohamed Fayed ◽  
Abdelhamid Attia
Keyword(s):  
Nusselt Number ◽  
Aspect Ratio ◽  
Average Nusselt Number ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Three Dimensional ◽  
Eccentric Annulus ◽  
Nano Fluid ◽  
Aspect Ratios ◽  
Laminar Forced Convection

Heat transfer through the horizontal eccentric annulus between eccentric rectangular ducts with different eccentricities has been calculated with various aspect ratio of inner duct. Boundary conditions are used with constant hot temperature on inner duct and constant cold temperature on the outer duct. Space between two ducts included TiO2-water Nano-fluid with different solid Volume fraction (φ = 0, 2, 5, 10 %). The eccentricity was changed with different values (E = 0.025, 0.05, 0.075 m) in left direction and aspect ratio was changed with different value (AR= 0.25, 0.375, 0.5). Results show that with an increase of aspect ratios, the average Nusselt number increases. Alsowith an increase in eccentricity value,the average Nusselt numberremains constant, and then an increase begins to occur. And the average Nusselt number increase due to an increase in nanoparticle concentration.

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