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Wyświetlanie 1-15 z 64
Tytuł:
The Gas dynamics of the exhaust diffusers: computational aspects
Autorzy:
Solodov, V. G.
Powiązania:
https://bibliotekanauki.pl/articles/1967649.pdf
Data publikacji:
2001
Wydawca:
Politechnika Gdańska
Tematy:
gas dynamics
diffusers
exhaust devices
CFD
computational fluid dynamics CFD
Opis:
Some recent advances in computational gas dynamics of exhaust diffusers are presented. The compressor/turbine axial-radial exhaust diffusers and outlet devices of compressor/turbine units, exhaust hoods for power steam turbines are considered. The peculiarities of gas dynamics of the above mentioned devices are discussed. The formulations of problems for CFD analysis of these devices are discussed including the coupling procedure for joint operation of the last stage and exhaust hood. The numerical method and the implementation of a differential turbulence model are described. The new approach to the description of computational domain and parallel numerical solution of transport equations based on the unstructured set of structured grid blocks is also presented.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2001, 5, 4; 495-517
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
2D simulations of liquid percolation through model porous media: preliminary MD and DPD results
Autorzy:
Rychcik, M.
Bośko, J.
Rybicki, J.
Alda, W.
Dzwinel, W.
Mancini, G.
Fioretti, L.
Powiązania:
https://bibliotekanauki.pl/articles/1964080.pdf
Data publikacji:
2001
Wydawca:
Politechnika Gdańska
Tematy:
2D flow simulations
particle methods
molecular dynamics
dissipative particle dynamics method
Opis:
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.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2001, 5, 1; 85-97
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelling of the static and dynamic properties of tho-type silicates
Autorzy:
Cauchi, R.
Grima, J. N.
Powiązania:
https://bibliotekanauki.pl/articles/1954447.pdf
Data publikacji:
2014
Wydawca:
Politechnika Gdańska
Tematy:
auxetics
zeolites
thomsonite
molecular dynamics
Opis:
Auxetic materials are materials exhibiting a negative Poisson’s ratio in one of their planes. This phenomenon has been studied in various materials. Zeolites are crystalline substances whose structure is characterised by the framework of linked tetrahedra, each consisting of four oxygen atoms surrounding a cation. The resulting interstitial spaces make them efficient for use as adsorbents and molecular sieves, and many studies have been focused on this aspect. Some of these zeolites may exhibit auxeticity at least in one of their planes. THO (and similar systems, such as NAT and EDI) together with the all-silica equivalent of these have been studied extensively via static simulations for their negative Poisson’s ratio in the (001) plane. In this paper a study of the all-silica equivalent of THO has been carried out via both static and dynamic simulations using the same force-field, where the system was subjected to stress along the x direction. The hypothesised semi-rigid mechanism of deformation, proposed by Grima et al. was then projected over this framework. The results obtained confirmed auxeticity along this plane by means of the COMPASS force-field, in both static and dynamic studies and compared well with the proposed mechanism of semi-rigid rotating polygons. It also showed that as the Young’s modulus of this mechanism increases other mechanisms of deformation increase in importance.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2014, 18, 1; 5-65
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical aspects of dynamic, geometrically non-linear calculations of elasto-viscoplastic plates
Autorzy:
Kłosowski, P.
Powiązania:
https://bibliotekanauki.pl/articles/1954536.pdf
Data publikacji:
1999
Wydawca:
Politechnika Gdańska
Tematy:
dynamics
viscoplasticity
finite element method
Opis:
In the paper numerical aspects of elasto-viscoplastic dynamic calculations of circular plates are presented. Numerical results are compared with experiments carried out in the laboratory. Each plate is calculated using the self-built computer program based on the finite element method. The Gaussian quadtrature is used for the surface integration and some difficulties concerning the choice of the order of this integration are discussed. To integrate the constitutive equations (the first order differential equations), and the equations of motion (the second order differential equations), it is necessary to use proper value of the time step. Some remarks on selection of this value are given. Density of the finite element mesh used for discretisation of the plate is studied. It was found that the number of elements has bigger influence on the quality of the results than t he number of layers used to describe the changes of stresses through the thickness of the plate. Finally, some comments on the choice of the model of damping are made. An approximate method of introduction of this factor in the calculations is presented.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 1999, 3, 2; 187-199
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of 3D flow solver in education of students
Autorzy:
Kosowski, K.
Powiązania:
https://bibliotekanauki.pl/articles/1931592.pdf
Data publikacji:
2002
Wydawca:
Politechnika Gdańska
Tematy:
computational fluid dynamics CFD
CFD
education
Opis:
The development of 3D numerical methods enables the estimation of flow parameters in any section of the channels and in this way the complex phenomenon of generation of losses can be investigated. Application of 3D solver helps in better understanding of flow behaviour in turbine stages, while basing on the results of calculations of stages of different geometries, it is possible to show the effect of different design parameters on the turbine stage output and its efficiency. The paper presents the examples of application of modern computer programs for teaching turbomachinery problems, for research flows in turbine stages and for solving design tasks. Some examples of students' projects are also included.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2002, 6, 4; 621-629
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A method of integration of molecular dynamics and continuum mechanics for solids
Autorzy:
Kaczmarek, J.
Powiązania:
https://bibliotekanauki.pl/articles/1963003.pdf
Data publikacji:
2002
Wydawca:
Politechnika Gdańska
Tematy:
continuum mechanics
molecular dynamics
multiscale modelling
Opis:
In this paper a formal system called collection of dynamical systems with dimensional reduction is considered. This is a multiscale method of mathematical description which allows to consider molecular dynamics and continuum mechanics within one theoretical framework. Transition between molecular dynamics and continuum mechanics is realized by means of the dimensional reduction procedure. In order to realize such a procedure the formulation of continuum mechanics is modified. This modification consists in incorporation scale of averaging for properties of processes considered during modelling into this formulation. As a result we introduce finite-dimensional fields on continuum only. All fundamental terms of continuum mechanics are now joined with an elementary dynamical system. In such a case continuum mechanics can be obtained by means of the dimensional reduction procedure applied to the elementary dynamical system. A numerical example of vibrating chain of material points is realized in order to show how in practice the dimensional reduction can be carried out. In this example decomposition of processes into slowly and quickly varying parts is accomplished. To this end a finite element representation of averaged fields is applied. Solutions of equations of the elementary dynamical system and the dimensionally reduced dynamical system are compared.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2002, 6, 2; 253-271
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Computer simulation of vibration surveillance of discretely idealised mechanical systems. Part I: Optimal control at the energy performance index for open non-stationary systems
Autorzy:
Kaliński, K. J.
Powiązania:
https://bibliotekanauki.pl/articles/1955706.pdf
Data publikacji:
2004
Wydawca:
Politechnika Gdańska
Tematy:
dynamics
control
simulation
railway weighing systems
Opis:
The paper discusses means of mechanical vibration surveillance using elements of control theory, dynamic optimisation, modern methods of computer simulation and measurement techniques. A mixed method of rigid and flexible finite elements is applied to discrete modelling of non-stationary controlled systems. A method of vibration surveillance in the time domain is elaborated, which utilises optimal control at the energy performance index with respect to the trajectory of given motion. An example is given of surveillance of transient vibration of a railway freight wagon weighing device.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2004, 8, 1; 79-87
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stability of finite-size argon thin film coating single wall carbon nanotube
Autorzy:
Kośmider, M.
Dendzik, Z.
Żurek, S.
Górny, K.
Powiązania:
https://bibliotekanauki.pl/articles/1964139.pdf
Data publikacji:
2009
Wydawca:
Politechnika Gdańska
Tematy:
nanotube
molecular dynamics
cluster
thin film
Opis:
The structure and the dynamics of the argon thin film coating (15,4) and (12,12) carbon nanotubes have been studied in a series of molecular dynamic simulations. In the studied temperature regime, the argon atoms in the thin film were well localized. Structural changes and diffusion process inside the argon layers were not been observed. The influence of the chirality and the radius of the nanotube to the cluster properties is also reported.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2009, 13, 3; 187-197
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study of icosahedral clusters in close-packed simple liquids
Autorzy:
Kozub, A.
Powiązania:
https://bibliotekanauki.pl/articles/1933986.pdf
Data publikacji:
2012
Wydawca:
Politechnika Gdańska
Tematy:
liquid metals
icosahedral clusters
structure
molecular dynamics
Opis:
The local structure of liquid copper was determined using Steinhardt order parameters, with particular attention paid to icosahedral clusters. The positions of atoms were obtained from three sets of molecular dynamics simulations, with the forces obtained from: the Sutton-Chen (SC) potential, the Naval Research Laboratory total energy tight-binding (NRL-TB) method and the divide-and-conquer learn-on-the-fly (DCLOTF) method, respectively. A broad range of local geometries appeared, which is a typical result for close-packed liquids. Among them a number of icosahedral clusters were detected. The highest density of icosahedral clusters was obtained at the temperature of 1000K for the NRL-TB and DCLOTF simulations and 1200K for the SC simulations. I propose various means of analysing the icosahedral clusters formed in liquid copper. The average number of the clusters, their lifetime and correlations between them at various temperatures were studied as a function of the approach used to generate the trajectories. Finally, I studied the formation and decay of icosahedral clusters.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2012, 16, 1-2; 75-96
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelling and simulation of dynamic unilateral elasto-plastic contact of compact hard bodies
Autorzy:
Kowalska, Z.
Powiązania:
https://bibliotekanauki.pl/articles/1986938.pdf
Data publikacji:
2002
Wydawca:
Politechnika Gdańska
Tematy:
motion simulation
nonlinear dynamics
vibro-impact systems
Opis:
The problems of modelling, simulation and analysis of vibro-impact motion of compact hard bodies are considered. In particular, dynamic elasto-plastic contact is simulated by using Johnson's analytical model of spherical bodies' contact. The results are compared with behaviour of the system with discrete linear-perfectly plastic model of contact.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2002, 6, 3; 335-341
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Smoothed particle hydrodynamics simulations using graphics processing units
Autorzy:
Szewc, K.
Powiązania:
https://bibliotekanauki.pl/articles/1954445.pdf
Data publikacji:
2014
Wydawca:
Politechnika Gdańska
Tematy:
fluid dynamics
CFD
particle methods
SPH
GPU calculations
Opis:
Smoothed Particle Hydrodynamics (SPH) is a fully Lagrangian, particle-based technique for fluid-flow modeling. As a gridless method, it appears to be a natural approach to simulate multi-phase flow with complex geometries. Since SPH involves a large set of short-range particle-particle interactions, numerical implementations present a high degree of spatial data locality and a significant number of independent computations. Therefore, the numerical code can be easily written in a massively parallel manner. The main purpose of this study is to discuss the issues related to the implementation of the SPH method for computation using Graphics Processing Units (GPU). The study is supported by two-dimensional validation cases: the lid-driven cavity and oscillation of a droplet. The obtained results show a good accuracy of the method, as well as, high numerical efficiency of its GPU implementation.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2014, 18, 1; 67-80
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Turbulent flow modelling using EARSM on parallel computers
Autorzy:
Sillen, M.
Powiązania:
https://bibliotekanauki.pl/articles/1955800.pdf
Data publikacji:
2001
Wydawca:
Politechnika Gdańska
Tematy:
aviation
computational fluid dynamics CFD
aerodynamics of airplanes
Opis:
The compressible Navier-Stokes equations are solved numerically for turbulent transonic aerospace applications on parallel computers. The turbulence is modelled by an Explicit Algebraic Reynolds Stress Model (EARSM). Expressing the EARSM as an extension of an eddy-viscosity model makes the implementation straightforward in a flow solver with existing two-equation eddy-viscosity models. The k-w transport equations are used as a platform for the model. The EARSM approach significantly improves the shock position for transonic flow over wings without substantial increase in computational cost. Industrial use of advanced flow modelling requires a short turn-around time of computations. This is enabled through the use of parallel computers. To achieve good parallel performance the computational load has to be evenly distributed between the processors of the parallel machine. A heuristic algorithm is described for distributing and splitting the blocks of a structured multiblock grid for a good static load balance. Speed-up results are presented for turbulent flow around a wing on a number of parallel platforms.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2001, 5, 2; 247-260
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of step errors (truncation errors) on results of molecular dynamics simulations
Autorzy:
Litniewski, M.
Powiązania:
https://bibliotekanauki.pl/articles/1986922.pdf
Data publikacji:
2002
Wydawca:
Politechnika Gdańska
Tematy:
error
molecular dynamics
symplectic
Verlet
Beeman
Cowell-Numerov
Opis:
Step errors (local errors, called also truncation errors) of the algorithms used in molecular dynamics simulations may result in non-physical correlations between particle velocities, as well as in errors of thermodynamic properties of simulated systems (energy, pressure). The simulations of the Lennard-Jones liquid showed, that the influence is especially high for the Verlet velocity algorithm. Beeman's technique decreases the correlations between the velocities, but at high densities the values of the errors of general averages are close to that of the Verlet method. The influence of step errors can be decreased by about two orders of magnitude by applying the Cowell-Numerov 4-th order implicit method (equivalent to the Gear 4-th order method treated as an implicit one). The method is very stable (more stable than the Verlet one), and can be highly optimized by restricting iteration to the closest neighbors of a given particle. As a result, the method becomes more efficient than the higher order explicit symplectic methods.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2002, 6, 3; 461-468
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
KAPPA - Karlsruhe parallel program for aerodynamics
Autorzy:
Magagnato, F.
Powiązania:
https://bibliotekanauki.pl/articles/1953984.pdf
Data publikacji:
1998
Wydawca:
Politechnika Gdańska
Tematy:
Karlsruhe Parallel Program for Aerodynamics
KAPPA
fluid dynamics
Opis:
Research in fluid dynamics can be done on both an experimental and numerical basis, For the latter a computer code needs to be written in order to solve the governing fluid flow equations. The KAPPA code is a CFD simulation package serving as a platform to develop faster and more accurate numerical schemes, better physical models, or as an engineering tool for the simulations of flows in technical equipment. Another important subject is the training and education of students or engineers. Since CFD is highly calculation intensive, new computer architectures such as vector and parallel computers are necessary to treat more complex flow fields or to resolve these flows more accurately. Therefore KAPPA has been specially designed to be used on these architectures. The structure of the code is such that the solution of additional transport equations needed for the simulation of chemistry, turbulence modeling, multiphase flows etc. can be easily implemented. In order to treat complex geometries the code is block structured. The finite volume method is used to discretize the equations in space. The code is written in Fortran 90 using the highly desirable new feature of this language. For the application of the code on parallel computers a message passing tool has been used.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 1998, 2, 2; 215-270
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical simulations of gap flow above rotating disk
Autorzy:
Wasilczuk, F.
Flaszyński, P.
Doerffer, P.
Powiązania:
https://bibliotekanauki.pl/articles/1938643.pdf
Data publikacji:
2015
Wydawca:
Politechnika Gdańska
Tematy:
computational fluid dynamics CFD
internal flow
flow control
Opis:
A rotating disk can be considered a basic configuration for the investigations of the impact of various conditions on the flow through the clearance between the shrouded turbine blade and the casing. Numerical calculations using Fine/Turbo Numeca were conducted to examine the influence of the rotational velocity and the pressure difference across the disk on the flow conditions, especially the mass flow through the clearance. The results were validated using the experimental data. Moreover, the flow field was investigated to reveal the vortices induced in the flow. The calculations showed a significant drop of the mass flow with a rise of the rotation velocity. Additionally, the vortex created upstream of the disk at higher rotation velocities was observed. The phenomenon of separation at the edge of the disk was investigated.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2015, 19, 2; 89-100
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 64

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