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Rise of the Poisson’s Ratio in f.c.c. Hard Sphere Crystals with the Narrowest Orthogonal Nanochannels Filled by Hard Spheres of Another Diameter

Narojczyk Jakub W., Tretiakov Konstantin V., Wojciechowski Krzysztof W.

Computational Methods in Science and Technology

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2022

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Vol. 28, No. 2

61--75

EN

Auxetic materials, i.e. materials exhibiting negative Poisson’s ratio, stand to answer the demand for novel materials with unique and application-tailored properties. The vast range of potential applications motivates researchers to search for new materials with such properties, or to look for ways to modify the properties of existing materials. The study of systems with structural inclusions falls into the latter category. This work reports numerical investigations of elastic properties of hard sphere f.c.c. crystal. The investigations have been focused on Monte Carlo simulations of systems with arrays of inclusions filled by hard spheres of different diameter, resulting in binary systems, i.e. systems composed of two kinds of particles that differ only in size. Two different layouts of narrow nanoinclusions have been studied in the isobaricisothermal ensemble. It has been shown that even the narrowest inclusions can significantly alter elastic properties of hard particle crystal by eliminating auxetic properties while maintaining the effective cubic symmetry.

2

Limitations of Applicability of the Green-Kubo Approach for Calculating the Thermal Conductivity of a Confined Liquid in Computer Simulations

Hyżorek K., Tretiakov K. V.

Computational Methods in Science and Technology

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2016

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Vol. 22, No. 4

197--200

EN

: Thermal conductivity (λ) of the Lennard-Jones liquid in cylindrical nanochannels has been determined using the Green-Kubo (GK) approach in equilibrium Molecular Dynamics simulations. Good convergence of λ(τ ) has been observed along the nanochannel’s axis where the periodic boundary conditions are applied. However, it has been found that the estimation of limiting value of λ(τ ) in the transverse direction, where walls confine the liquid, is ambiguous.

3

Analytical solutions of electro-kinetic flow in nano-fluidic components by using He’s homotopy perturbation method

Khaki M., Taeibi-Rahni M., Ganji D. D.

Journal of Theoretical and Applied Mechanics

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2013

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Vol. 51 nr 2

265--274

EN

This paper aims to examine the electro-kinetic flow through nano-channels. The equations governing the fluid flow in a one dimensional channel are derived from the Poisson-Nernst-Planck theory. The boundary conditions for the governing equations are obtained from the electrochemical equilibrium requirements. The coupled equations are transformed into a single differential equation. The transformed equation is solved by He’s homotopy perturbation method and an exact solution is achieved. The validity of results is verified by comparing with existing numerical results. The results are presented for velocity profiles, electrical potential distributions, mole fraction of cation and anion distributions and other physical properties. The results demonstrate reasonable agreement with those provided by other numerical methods and good accuracy of the obtained analytical solutions.

PL

Celem pracy jest przedstawienie wyników badań nad elektrokinetycznym przepływem cieczy przez nano-kanały. Równania opisujące przepływ w jednowymiarowym kanale wyprowadzono na podstawie teorii Poissona-Nernsta-Plancka. Warunki brzegowe uzyskano po spełnieniu wymogów równowagi elektrochemicznej układu. Sprzężone równania przepływu przekształcono do postaci pojedynczego równania różniczkowego. Następnie rozwiązano go za pomocą perturbacyjnej metody homotopii He’go, otrzymując wyrażenie analityczne i dokładne. Poprawność rezultatów sprawdzono, porównując je z istniejącymi wynikami symulacji numerycznych. Zaprezentowano profile prędkości przepływu, rozkłady potencjału elektrycznego, molowe udziały frakcji anionów i kationów oraz inne parametry fizyczne układu. Wszystkie wyniki wykazały dobrą zgodność z obliczeniami opartymi na innych metodach badawczych, co potwierdziło dokładność otrzymanych rozwiązań analitycznych.

4

Molecular dynamics computer simulation of water flows in nanochannels

Kucaba-Piętal A., Walenta Z.A., Peradzyński Z.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2009

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Vol. 57, nr 1

55-61

EN

The work presents the results of the simulations of water flows through narrow channels (Poiseuille flows) performed using the molecular dynamics method, for two different channel widths (equal to 5 and 10 diameters of the water molecule) and for two different materials of the channel walls (copper and quartz). In the simulations, physical properties of the materials and their electrostatic interactions were considered. The obtained results are compared with the analytical solutions for a micropolar fluid flow taking account of the experimentally obtained rheological constants of water.