Wyniki wyszukiwania - BazTech

1

Modelling of hemodynamics in 3D bypass models

Vimmr J., Jonasova A.

Modelling and Optimization of Physical Systems

|

2010

|

z. 9

87--92

EN

The study is divided into two parts. The first one deals with the modelling of non-Newtonian effects in occluded femoral bypass considering steady blood flow. The second part is devoted to the analysis of pulsatile Newtonian blood flow in stenosed coronary bypass applying realistic inlet flow rates. The bypass models are assumed to be idealized and complete, i.e. the native artery and the bypass graft are modelled as tubes with both proximal and distal parts. The governing equations are solved numerically with explicit and implicit schemes formulated in the sense of the finite volume method using developed in-house software.

CS

Tato studie je rozdělena na dvě části. První se zabývá modelováním nenewtonských efektů ve femorálním bypassu pří uvažováni ustáleného proudění krve. Druhá část je věnována analýze pulzujícího proudění krve jakožto newtonské kapaliny v koronárním bypassu. Matematický model je řešen pomocí explicitních a implicitních schémat formulovaných ve smyslu metody konečných objemů a za použití vlastního vyvinutého softwaru.

2

Influence of junction angle on hemodynamics in a bypass model

Vimmr J., Jonasova A.

Modelling and Optimization of Physical Systems

|

2007

|

z. 6

153--156

EN

The problem of steady laminar flow of an incompressible Newtonian fluid through an idealized 2-D bypass model with a stenosed coronary artery is solved using the finite volume approach of the MacCormack and Runge-Kutta schemes. The bypass model includes proximal and distal parts of the artery together with end-to-side graft. The changes of hemodynamics are investigated with three different junction angles (ɑ = 20°,45°,70°) between the graft and the artery. The velocity and wall shear stress distributions obtained using both numerical schemes for all three cases are analyzed and compared with each other.

3

Numerical simulation of leakage flow between moving rotor and housing of screw compressor

Vimmr J., Fryc O.

Modelowanie Inżynierskie

|

2006

|

T. 1, nr 32

461-468

EN

Mathematical modelling of transonic flow of viscous compressible fluids in very narrow channels and gaps is one of the very topical and demanding problems of fluid dynamics today. This article presents the numerical simulations of leakage flow in a narrow channel formed by a tooth of male rotor and housing in a screw compressor. The influence of the male rotor motion on the compressible viscous flow through the clearance gap for various male rotor angular velocities is observed. The dependence of simulation results on different numerical grids is rated and the sufficiently coarse grid for obtaining reasonable results is searched. The influence of turbulence models on obtained numerical results is investigated.

4

Introduction to the mathematical modelling of turbulent compressible fluid flow

Vimmr J.

Zeszyty Naukowe Katedry Mechaniki Stosowanej / Politechnika Śląska

|

2003

|

nr 21

207-212

EN

This contribution is devoted to the theory of the mathematical modelling of turbulent compressible fluid flow. The paper briefly reviews the conservative system of the Navier-Stokes equations for laminar compressible flows. The Reynolds and Favre mass-averaging procedure is introduced. The main attention of this work is turned towards the derivation of the Favre-averaged Navier-Stokes equations based on the most commonly used closure approximations for compressible flows. The modem Baldwin-Lomax algebraic turbulence model is discussed.

5

Contribution to the mathematical modelling of the fluid flow in screw machines

Vimmr J., Svigler J.

Zeszyty Naukowe Katedry Mechaniki Stosowanej / Politechnika Śląska

|

2002

|

nr 18

421-426

EN

The mathematical modelling of compressible flow belongs to challenging problems of internal aerodynamics, examples of which can be found in many areas of industry, for instance in screw compressors. This paper is deyoted to the numerical computation of the 3D stationary inviscid transonic flow in internal aerodynamics. For the numerical solution of this system the cell-centred finite volume formulation of the explicit two-step MacCormack scheme with Jameson's artificial dissipation is used.

6

Preliminary analysis of the fluid flow in screw compressors

Svigler J., Vimmr J.

Zeszyty Naukowe Katedry Mechaniki Stosowanej / Politechnika Śląska

|

2000

|

z. 12

79-82

EN

In addition to kinematic and dynamic analyses of screw compressors it is necessary to turn our attention to the internal fluid dynamics of the screw compressors. This paper presents numerical computation of compressible inviscid flow in the work space of the screw compressor and through the gaps on its boundary. The mathematical model is described by the conservative system of euler equations. The numerical solution of this system is based on a finite difference and finite volume methods utilized on a structured quadrilateral mesh. The results are verified with the software package Fluent 5.0.2.