scholarly journals The influence of particle size to diffusivity of nanogold particles based on Brownian motion

2020 ◽  
Vol 1528 ◽  
pp. 012042
Author(s):  
Zulfahmi ◽  
Djati Handoko ◽  
Prawito Prajitno ◽  
Isnaeni
Keyword(s):  
Particle Size ◽  
Brownian Motion ◽  
Nanogold Particles

Die Gelchromatographie großer Partikel und ihre Grenzen / Limitation of Particles Size in Gel Chromatography

1970 ◽  
Vol 25 (11) ◽  
pp. 1235-1239 ◽  
Author(s):  
Wolfram Gerlich ◽  
Helmut Determann ◽  
Theodor Wieland
Keyword(s):  
Particle Size ◽  
Brownian Motion ◽  
Rat Liver ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Gel Chromatography ◽  
Particle Sizes ◽  
E Coli ◽  
Large Particles ◽  
Cellulose Gel

The behaviour of molecules and particles of 2 - 400 nm radius in gel chromatography was investigated using sephadex, agarose, and pearl shaped cellulose gel of different porosity. Correlations between elution volumes and particle sizes are given in Fig. 1. We found that particles from ca. 400 nm diameter upwards were more or less irreversibly adsorbed depending on the particle size. So only 15% of rat liver mitochondria and 5% of E. coli bacteria could be eluted from the loose cellulose Cu3. It is assumed that this adsorption is due to the absence of Brownian motion of large particles, which therefore are more or less subject to the gravity and to adsorption forces of the gel.

Stability of Zinc Oxide Nanofluids Prepared with Aggregated Nanocrystalline Powders

2008 ◽  
Vol 8 (12) ◽  
pp. 6361-6366
Author(s):  
J. P. Leonard ◽  
S. J. Chung ◽  
I. Nettleship ◽  
Y. Soong ◽  
D. V. Martello ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Particle Size ◽  
Zinc Oxide ◽  
Brownian Motion ◽  
Preparation Method ◽  
Volume Fraction ◽  
High Volume ◽  
Nanocrystalline Powders ◽  
Zno Powder ◽  
20 Nm

Aqueous zinc oxide (ZnO) suspensions were prepared using a two-step preparation method in which an aggregated nanocrystalline ZnO powder was dispersed in water using a polyelectrolyte. The fluid showed anomalously high thermal conductivity when compared with the Maxwell and Hamilton-Crosser predictions. However, analysis of the particle size distribution showed that the fluid contained aggregated 20 nm crystallites of ZnO with a high volume fraction of particles larger than 100 nm. Sedimentation experiments revealed that particles settled out of the stationary fluid over times ranging from 0.1 hours to well over 10,000 hours. The size of the particles remaining in suspension agreed well with predictions made using Stoke's law, suggesting flocculation was not occurring in the fluids. Finally, a new concept of nanofluid stability is introduced based on the height of the fluid, sedimentation, Brownian motion and the kinetic energy of the particles.

scholarly journals Monte Carlo simulation of coagulation in discrete particle-size distributions. Part 1. Brownian motion and fluid shearing

1984 ◽  
Vol 143 ◽  
pp. 367-385 ◽  
Author(s):  
H. J. Pearson ◽  
I. A. Valioulis ◽  
E. J. List
Keyword(s):  
Monte Carlo Simulation ◽  
Particle Size ◽  
Monte Carlo ◽  
Brownian Motion ◽  
Size Distributions ◽  
Unit Size ◽  
Particle Size Distributions ◽  
Maximum Volume ◽  
Discrete Particle ◽  
Constant Rate

A method for the Monte Carlo simulation, by digital computer, of the evolution of a colliding and coagulating population of suspended particles is described. Collision mechanisms studied both separately and in combination are: Brownian motion of the particles, and laminar and isotropic turbulent shearing motions of the suspending fluid. Steady-state distributions are obtained by adding unit-size particles at a constant rate and removing all particles once they reach a preset maximum volume. The resulting size distributions are found to agree with those obtained by dimensional analysis (Hunt 1982).

Estimating Al2O3–CO2 nanofluid viscosity: a molecular dynamics approach

2018 ◽  
Vol 84 (3) ◽  
pp. 30902
Author(s):  
Zeeshan Ahmed ◽  
Atul Bhargav ◽  
Sairam S. Mallajosyula
Keyword(s):  
Molecular Dynamics ◽  
Particle Size ◽  
Brownian Motion ◽  
Oil Recovery ◽  
Interaction Potential ◽  
Base Fluid ◽  
Oil And Gas Industry ◽  
Distribution Functions ◽  
Interatomic Potentials ◽  
Increase With Increase

High-viscosity CO2 is of interest to the oil and gas industry in enhanced oil recovery and well-fracturing applications. Dispersing nanoparticles in CO2 is one way of achieving increased viscosity. However, parametric studies on viscosity estimation of CO2 nanofluids is not found in the open literature. A comparison of various interatomic potentials for their accuracy in predicting viscosity is also missing. In this work, we studied Al2O3 nanoparticles in CO2 base fluid. We screened the inter-molecular interaction potential models available for CO2–CO2 interactions and found that the TraPPE-flexible model (with MORSE potential) to be most suitable for conditions used in this work. We estimated the CO2–Al2O3 interaction potential using quantum mechanical simulations. Using this combination for CO2–CO2 and CO2–Al2O3 interactions, we explored the effects of temperature and nanoparticle size on viscosity using molecular dynamics simulations (MD). We predicted that the viscosity would increase with increase in temperature and particle size. We also calculated the base fluid self-diffusion coefficient to investigate the effect of Brownian motion and its contribution to changes in viscosity. We found that it decreases with increase in particle size and temperature, thereby indicating that Brownian motion does not contribute to the increased viscosity. Further, the nanolayer formed at the Al2O3–CO2 interface is studied through density distributions around the nanoparticle; the thickness of this nanolayer is found to increase with nanoparticle diameter. Finally, we examined the structures of CO2 fluid in presence of nanoparticles at different thermodynamic states through radial distribution functions. The current work sheds light on the viscosity enhancement by the addition of nanoparticles; it is hoped that such studies will lead to tools that help tailor fluid properties to specific requirements.

Parametric Analysis of Effective Thermal Conductivity Models for Nanofluids

2012 ◽  
Author(s):  
Mohsen Sharifpur ◽  
Tshimanga Ntumba ◽  
Josua P. Meyer
Keyword(s):  
Thermal Conductivity ◽  
Particle Size ◽  
Brownian Motion ◽  
Effective Thermal Conductivity ◽  
Parametric Analysis ◽  
Base Fluid ◽  
Volume Fraction ◽  
Hybrid Models ◽  
The Impact ◽  
Conductivity Models

There is a lack of reported research on comprehensive hybrid models for the effective thermal conductivity of nanofluids that takes into consideration all major mechanisms and parameters. The major mechanisms are the nanolayer, Brownian motion and clustering. The recognized important parameters can be the volume fraction of the nanoparticles, temperature, particle size, thermal conductivity of the nanolayer, thermal conductivity of the base fluid, PH of the nanofluid, and the thermal conductivity of the nanoparticle. Therefore, in this work, a parametric analysis of effective thermal conductivity models for nanofluids was done. The impact of the measurable parameters, like volume fraction of the nanoparticles, temperature and the particle size for the more sited models, were analyzed by using alumina-water nanofluid. The result of this investigation identifies the lack of a hybrid equation for the effective thermal conductivity of nanofluids and, consequently, more research is required in this field.

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