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1.
Avtomatiziran preračun krožnih transporterjev
Zoran Žunič, 1992, diplomsko delo

Ključne besede: transportne naprave
Objavljeno: 26.07.2007; Ogledov: 1379; Prenosov: 0

2.
SIMULACIJA MOTORJA V REALNEM ČASU - DELOVNI TOK IN NASTAVITEV HIL MODELA MOTORJA
Mihael Humar, 2011, diplomsko delo

Opis: Podan motor je bil merjen na testni mizi v laboratoriju. Želja je bila, da se ta motor še preračuna v računalniškem programu BOOST RT. Motor se je najprej zmodeliral,vstavili so se vsi elementi, kateri so potrebni za brezhibno delovanje motorja. Tem elementom so se podali pravilni podatki, katere je bilo potrebno zbrati iz meritev motorja. Preračun motorja v prvi fazi ni podal ustreznih rezultatov, zato se ga je, s pomočjo vrednosti zbranih v grafih, optimiralo. Najpomembnejše vrednosti za popolno delovanje so bili: tlaki v motorju, navor motorja in turbokompresorja, masni tokovi in kvaliteta zraka v turbokompresorju, izkoristki ter hitrosti turbokompresorja.
Ključne besede: motor z notranjim zgorevanjem, turbokompresor, programa BOOST in BOOST RT, simulacija modela, tlaki v motorju.
Objavljeno: 13.10.2011; Ogledov: 1636; Prenosov: 218
.pdf Celotno besedilo (2,06 MB)

3.
Non-Newtonian fluid flow through a planar symmetric expansion: shear thickenning fluids
Primož Ternik, Jure Marn, Zoran Žunič, 2006, izvirni znanstveni članek

Opis: The incompressible non-Newtonian fluid flow through a symmetric sudden expansion is studied numerically in order to obtain Reynolds number critical value. The Quadratic model is employed to accommodate the shear-thickening behavior of corn-starch and water mixture. Numerical procedure is validated with results for the Newtonian fluid flow in a range of the Reynolds number Re=10,20,.,100. Results for the non-Newtonian fluid show that the shear-thickening behavior lowers the threshold of the transition from flow symmetry to its asymmetry (lowers the onset of the bifurcation and the critical value of the Reynolds number) and increases the reattachment length. In addition, the results for the Quadratic model are compared to the results obtained with the Power law.
Ključne besede: fluid mechanics, bifurcation, sudden expansion, shear thickenningfluid, quadratic model, powr law
Objavljeno: 31.05.2012; Ogledov: 959; Prenosov: 22
URL Povezava na celotno besedilo

4.
Velocity-vorticity formulation for 3D natural convection in an inclined enclosure by BEM
Jure Ravnik, Leopold Škerget, Zoran Žunič, 2008, izvirni znanstveni članek

Opis: A natural convection phenomenon is studied in cubic and parallelepipedal inclined enclosures. The simulation of coupled laminar viscous flow and heat transfer is performed using a novel algorithm based on a combination of singledomain Boundary element method (BEM) and subdomain BEM. The algorithm solves the velocity-vorticity formulation of the incompressible Navier-Stokes equations coupled with the energy equation using the Boussinesq approximation.The subdomain BEM is used to solve the kinematics equation, the vorticity transport equation and the energy equation. The boundary vorticity values, which are needed as boundary conditions for the vorticity transport equation, are calculated by singe domain BEM solution of the kinematics equation. Simulation results are compared with benchmark results for a cubic inclined enclosure for Rayleigh number values ▫$10^3Ključne besede: podobmočna metoda robnih elementov, hitrostno-vrtinčna formulacija, laminarni tok viskozne tekočine, naravna konvekcija, nagnjena kotanja, fluid mechanics, subdomain boundary element method, velocity-vorticity formulation, laminar viscous fluid flow, natural convection, inclined enclosure
Objavljeno: 31.05.2012; Ogledov: 1465; Prenosov: 55
URL Povezava na celotno besedilo

5.
Numerična analiza termo hidravličnih razmer v avtomobilski meglenki
Matjaž Ramšak, Zoran Žunič, Leopold Škerget, Tomaž Jurejevčič, 2008, objavljeni znanstveni prispevek na konferenci

Opis: V prispevku obravnavamo vezan prenos toplote v trdnini in tekočini znotraj avtomobilske meglenke s programom za ra¡cunalniško dinamiko tekočin CFX [1]. Modelirani so vsi trije osnovni mehanizmi prenosa toplote: difuzija, konvekcija in sevanje. Predstavili bomo dva pristopa k modeliranju sevanja. Prav tako primerjamo rezultate izračunane kot laminarni in turbulentni tok, ker ocenjeno Raylightovo število nakazuje prehodni režim. Rezultati se dobro ujemajo z meritvami.
Ključne besede: prenos toplote, računalniška dinamika tekočin, halogenske žarnice, termične napetosti
Objavljeno: 31.05.2012; Ogledov: 890; Prenosov: 32
URL Povezava na celotno besedilo

6.
Comparison between wavelet and fast multipole data sparse approximations for Poisson and kinematics boundary - domain integral equations
Jure Ravnik, Leopold Škerget, Zoran Žunič, 2009, izvirni znanstveni članek

Opis: The boundary element method applied on non-homogenous partial differential equations requires calculation of a fully populated matrix of domain integrals. This paper compares two techniques: the fast multipole method and the fast wavelet transform, which are used to reduce the complexity of such domain matrices. The employed fast multipole method utilizes the expansion of integral kernels into series of spherical harmonics. The wavelet transform for vectors of arbitrary length, based on Haar wavelets and variable thresholding limit, is used. Both methods are tested and compared by solving the scalar Poisson equation and the velocity-vorticity vector kinematics equation. The results show comparable accuracy for both methods for a given data storage size. Wavelets are somewhat better for high and low compression ratios, and the fast multipole methods gives better results for moderate compressions. Considering implementation of the methods, the wavelet transform can easily be adapted for any problem, while the fast multipole method requires different expansion for each integral kernel.
Ključne besede: wavelets, fast multipole method, Poisson equation, BEM
Objavljeno: 31.05.2012; Ogledov: 1343; Prenosov: 53
URL Povezava na celotno besedilo

7.
Fast single domain-subdomain BEM algorithm for 3D incompressible fluid flow and heat transfer
Jure Ravnik, Leopold Škerget, Zoran Žunič, 2009, izvirni znanstveni članek

Opis: In this paper acceleration and computer memory reduction of an algorithm for the simulation of laminar viscous flows and heat transfer is presented. The algorithm solves the velocity-vorticity formulation of the incompressible Navier-Stokes equations in 3D. It is based on a combination of a subdomain boundary element method (BEM) and single domain BEM. The CPU time and storage requirements of the single domain BEM are reduced by implementing a fast multipole expansion method. The Laplace fundamental solution, which is used as a special weighting function in BEM, is expanded in terms of spherical harmonics. The computational domain and its boundary are recursively cut up forming a tree of clusters of boundary elements and domain cells. Data sparse representation is used in parts of the matrix, which correspond to boundary-domain clusters pairs that are admissible for expansion. Significant reduction of the complexity is achieved. The paper presents results of testing of the multipole expansion algorithm by exploring its effect on the accuracy of the solution and its influence on the non-linear convergence properties of the solver. Two 3D benchmark numerical examples are used: the lid-driven cavity and the onset of natural convection in a differentially heated enclosure.
Ključne besede: boundary element method, fast multipole method, fluid flow, heat transfer, velocity-vorticity fomulation
Objavljeno: 31.05.2012; Ogledov: 1268; Prenosov: 37
URL Povezava na celotno besedilo

8.
9.
CFD analysis of exothermic reactions in Al-Au nano multi-layered foils
Karlo Raić, Rebeka Rudolf, Primož Ternik, Zoran Žunič, Vojkan Lazić, Dragoslav Stamenković, Tatjana Tanasković, Ivan Anžel, 2011, izvirni znanstveni članek

Opis: This work presents the possibility of numerical modelling using Computational Fluid Dynamics (CFD) in the field of nano-foils. The governing equations were solved using a Finite Volume Methodology (FVM). The computational domain was discretized using a uniform Cartesian grid with the appropriate mesh size along the x and y directions employing the corresponding number of grid points. The field variables were discretized at the cell centres and the spatial, as well as the time, derivatives were approximated using the second-order accurate numerical scheme. The time-evolution of the temperature and concentration fields, as well as the atomic diffusion coefficient, will be presented for the appropriate Al-Au nano-foil geometry and boundary conditions.
Ključne besede: Au-Al nano-foils, finite volume method, temperature transfer, concentration transfer
Objavljeno: 01.06.2012; Ogledov: 950; Prenosov: 56
.pdf Celotno besedilo (526,41 KB)
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