Contents:

  • Krzysztof W. Wojciechowski and Vitaly V. Novikov Negative Poisson's Ratio and Percolating Structures   abstract | full text
  • Violetta Konopińska, Sławomir Telega and Józef E. Sienkiewicz Electron-Argon Scattering: a High Angle Minimum in Differential Cross Sections   abstract | full text
  • Michał Banaszak Molecular Dynamics Simulation of Copolymers   abstract | full text
  • Agnieszka Herman and Andrzej Jankowski Wind- and Density-Driven Water Circulation in the Southern Baltic Sea: a Numerical Analysis   abstract | full text
  • Remigiusz Górecki, Maksymilian Mars, Witold Alda, Lauro Fioretti and Jarosław Rybicki Simulation of Fluid Flow with Interacting Particles   abstract | full text
  • Nadaniela Egidi, Luciano Misici and Riccardo Piergallini Laminar Mixing Flow in a Stirred Vessel   abstract | full text
  • Monika Rychcik, Jarosław Bosko, Jarosław Rybicki, Witold Alda, Witold Dzwinel, Giorgio Mancini and Lauro Fioretti 2D Simulations of Liquid Percolation through Model Porous Media: Preliminary MD and DPD Results   abstract | full text
  • Lauro Fioretti and Massimo Conti Heat Transfer Analysis for the Hydraulic Circuit of an Expresso-Coffee Machine   abstract | full text
  • Andrzej Januszajtis Secrets of Golden Vodka   abstract | full text

Abstracts:

hKrzysztof W. Wojciechowski and Vitaly V. Novikov Negative Poisson's Ratio and Percolating Structures

Elastic properties of non-uniform, two-component systems are studied in frames of a model of percolation on a simple cubic lattice. It is shown that as the ratio of the bulk moduli of the components tends to zero,  = K s / K h ! 0 (where s,h denote the softer and harder phase, respectively), the Poisson's ratio of the system tends to 0.2 at the percolation threshold of the harder phase, no matter what the values are of the Poisson's ratios of the components. A qualitatively new, collective mechanism leading to negative Poisson's ratio is suggested.

 

hVioletta Konopińska, Sławomir Telega and Józef E. Sienkiewicz Electron-Argon Scattering: a High Angle Minimum in Differential Cross Sections

Ab initio relativistic calculations of the high angle differential cross section minimum have been presented. Theoretical method is based on the Dirac-Hartree-Fock scattering equation. Ab initio polarization and exact exchange have been included. Calculations have been performed for the low energy elastic electron scattering from argon. A very good agreement with the recent experimental data has been found.

 

hMichał Banaszak Molecular Dynamics Simulation of Copolymers

A series of representative Molecular Dynamics simulations of model Lennard-Jones copolymer chains is presented. We report measurements of thermodynamic, structural and dynamic properties of our model copolymers. For neutral copolymers we confirm our version of Thermodynamic Perturbation Theory of the First Order, while for ionic copolymers we demonstrate microphase formation and the anisotropy of the counterion diffusion.

 

hAgnieszka Herman and Andrzej Jankowski Wind- and Density-Driven Water Circulation in the Southern Baltic Sea: a Numerical Analysis

The study focuses on the hydrodynamic processes in the southern Baltic Sea, with special interest in the Stolpe Channel – the only deep water connection between Bornholm Basin to the west and Gdansk and Gotland Basins to the east. The Channel is an area of strong interactions of wind- and density-driven currents that may lead to a complex flow structure. A three-dimensional numerical model was applied to an analysis of processes mentioned above. Three model versions of different spatial resolution (5, 3 and 1Nm) were used to investigate an influence of this parameter on the model results. The simulations were performed for four main wind directions, for a variable in time wind speed. It was shown that water circulation in the southern Baltic is to a high degree dependent on local anemobaric conditions. The results confirm the hypothesis of Krauss and Brügge that the flow in the Channel is opposite to the wind direction. Numerical grid step can have a decisive influence on the modeled circulation patterns, especially when barotropic and baroclinic flow components counteract. In such situations – when the flow is bidirectional and mesoscale eddies are generated – high resolution of the model is particularly important.

 

hRemigiusz Górecki, Maksymilian Mars, Witold Alda, Lauro Fioretti and Jarosław Rybicki Simulation of Fluid Flow with Interacting Particles

In the paper a method for modeling flows in the presence of interacting particles is briefly presented. The method is based on merging classical, continuous approach of numerical solution of NavierStokes equations on the 2D mesh with discrete particles interacting with the fluid and among themselves by means of central and friction forces. Several sample simulations have been described presenting the flow through porous medium and convection flow driven by sedimentation.

 

hNadaniela Egidi, Luciano Misici and Riccardo Piergallini Laminar Mixing Flow in a Stirred Vessel

Using finite element method we study the transient motion of fluid particles in a 3D cavity, when the fluid is incompressible viscous and with uniform density. The fluid is mixed under the action of four-blades turbine that is simulated by a velocity function. The mixing quality of the fluid is studied qualitatively, by visualization, and quantitatively, by measurering the indices of diffusion and dispersion.

 

hMonika Rychcik, Jarosław Bosko, Jarosław Rybicki, Witold Alda, Witold Dzwinel, Giorgio Mancini and Lauro Fioretti 2D Simulations of Liquid Percolation through Model Porous Media: Preliminary MD and DPD Results

In the paper we make a short overview of computer models based on particle approach, which can be suitable for the simulation of fluid flow through porous media. We concentrate on Molecular Dynamics (MD) and Dissipative Particle Dynamics (DPD) methods. We describe main features of our simulation programs, and present and discuss preliminary results of MD and DPD simulations of 2D fluid flow through a simple model rigid porous media. The paper aims at the evaluation of the applicability of MD and DPD methods for simulations of liquid flows in media of complicated geometry.

 

hLauro Fioretti and Massimo Conti Heat Transfer Analysis for the Hydraulic Circuit of an Expresso-Coffee Machine

An Espresso-Coffee Machine supplies water whose temperature must be confined within a narrow range in different operating conditions; this requires an accurate design at the component as well as the system level. In the present paper we develop a mathematical model to analyse the performances of the heating circuit of such a machine; our aim is to capture the main operating characteristics of the system with the maximum of simplicity. The governing equations of the model have been solved with the finite difference technique, and the first results have been compared with some experimental data.

 

hAndrzej Januszajtis Secrets of Golden Vodka

 

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