Composition Fluctuations in the Ostwald Ripening

2008 ◽  
Vol 277 ◽  
pp. 187-192
Author(s):  
G.V. Lutsenko ◽  
Andriy Gusak
Keyword(s):  
Computer Simulation ◽  
Particle Size ◽  
Large Volume ◽  
Ostwald Ripening ◽  
Volume Fraction ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Two Phase ◽  
Large Volume Fraction ◽  
Composition Fluctuations

The Ostwald ripening of a two-phase binary alloy has been considered for case of “large” volume fraction of precipitating phase. The approach is proposed in which the composition fluctuations into the vicinity of particles are considered. In this approach the evolution of particle size distributions is analyzed using the computer simulation.

scholarly journals COMPUTER SIMULATION OF RANDOM PACKINGS FOR SELF-SIMILAR PARTICLE SIZE DISTRIBUTIONS IN SOIL AND GRANULAR MATERIALS: POROSITY AND PORE SIZE DISTRIBUTION

Fractals ◽  
2014 ◽  
Vol 22 (03) ◽  
pp. 1440009 ◽  
Author(s):  
MIGUEL ANGEL MARTÍN ◽  
FRANCISCO J. MUÑOZ ◽  
MIGUEL REYES ◽  
F. JAVIER TAGUAS
Keyword(s):  
Computer Simulation ◽  
Particle Size ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Total Porosity ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Self Similar ◽  
Random Packings

A 2D computer simulation method of random packings is applied to sets of particles generated by a self-similar uniparametric model for particle size distributions (PSDs) in granular media. The parameter p which controls the model is the proportion of mass of particles corresponding to the left half of the normalized size interval [0,1]. First the influence on the total porosity of the parameter p is analyzed and interpreted. It is shown that such parameter, and the fractal exponent of the associated power scaling, are efficient packing parameters, but this last one is not in the way predicted in a former published work addressing an analogous research in artificial granular materials. The total porosity reaches the minimum value for p = 0.6. Limited information on the pore size distribution is obtained from the packing simulations and by means of morphological analysis methods. Results show that the range of pore sizes increases for decreasing values of p showing also different shape in the volume pore size distribution. Further research including simulations with a greater number of particles and image resolution are required to obtain finer results on the hierarchical structure of pore space.

Three Dimensional Monte Carlo Simulation of Isotropic Coarsening of Particles in Liquid Phase

2007 ◽  
Vol 558-559 ◽  
pp. 1115-1120
Author(s):  
Suk Bin Lee ◽  
Anthony D. Rollett
Keyword(s):  
Particle Size ◽  
Monte Carlo ◽  
Liquid Phase ◽  
Ostwald Ripening ◽  
Monte Carlo Model ◽  
Liquid Phase Sintering ◽  
Three Dimensions ◽  
Average Particle ◽  
Size Distributions ◽  
Particle Size Distributions

Coarsening of particles during liquid phase sintering is known to be an example of Ostwald ripening. This coarsening process, in a fully wetting system, is simulated in three dimensions with a kinetic Monte Carlo model. The results from the simulation for microstructures, kinetics and particle size distributions are compared to available experimental findings. It is found that the average particle volume increases linearly with time and that the particle size distributions are consistent with those obtained experimentally, as in the W-Ni-Fe and Sn-Pb systems.

A Soot Chemistry Model That Captures Fuel Effects

2014 ◽  
Author(s):  
Karthik V. Puduppakkam ◽  
Abhijit U. Modak ◽  
Chitralkumar V. Naik ◽  
Joaquin Camacho ◽  
Hai Wang ◽  
...  
Keyword(s):  
Particle Size ◽  
Soot Particle ◽  
Volume Fraction ◽  
Soot Volume Fraction ◽  
Surface Model ◽  
Particle Nucleation ◽  
Size Distributions ◽  
Surface Kinetics ◽  
Particle Size Distributions ◽  
Detailed Chemistry

A detailed chemistry model is necessary to simulate the effects of variations in fuel composition on soot emissions. In this work, we have developed a detailed chemistry model for the soot formation and oxidation chemistry, with a focus on the surface kinetics of the soot-particle. The model has been compared to a unique set of soot particle-size data measured in flames for several single-component fuels. Fuel components used in the experiments represent the chemical classes found in jet, gasoline, and diesel fuels, including n-heptane (representative of n-alkanes) and toluene (aromatic). Measurements were taken in burner-stabilized stagnation-flame (BSSF) experiments, which can be simulated well using the 1-dimensional BSSF flame model in CHEMKIN-PRO. Soot volume fraction and particle size distributions are modeled using the sectional method option for Particle Tracking, within CHEMKIN-PRO software. The well-characterized flow of the BSSF experiments allows the modeling to focus on the kinetics. Validated detailed reaction mechanisms for fuel combustion and PAH production, combined with the new soot surface-kinetics mechanism, were used in the simulations. Simulation results were compared to measurements for both particle size distributions and total soot volume fraction. Observed effects of fuel, temperature, pressure, equivalence ratio and residence time on the soot size distribution shape and soot quantity were reproduced by the model. The chemistry in the soot surface model includes particle nucleation, growth through the HACA (hydrogen-abstraction/carbon-addition) and PAH-condensation (polycyclic aromatic hydrocarbons) pathways, as well as soot-oxidation pathways. In addition to soot chemistry, the physics of particle coagulation and aggregation were included in the model. The results demonstrate the ability of well-validated chemistry to predict both dramatic and subtle effects related to soot mass and soot particle size.

Sign in / Sign up

Export Citation Format

Share Document