Wyniki wyszukiwania - Biblioteka Nauki

1

Forced convection in heterogeneous porous media: the effect of thermal dispersion

100%

Kuznetsov A. V.

International Journal of Applied Mechanics and Engineering

|

2002

|

tom Vol. 7, no 2

565-590

EN

This paper presents a new analytical solution to a problem of forced convection in a heterogeneous channel filled with two different layers of isotropic porous media. The Brinkman-Forchheimer-extended Darcy equation is utilized to describe the fluid flow in the porous layers, and the effect of transverse thermal dispersion is accounted for in the energy equations. Three momentum boundary layers are identified in the channel: a boundary layer at the solid wall and two boundary layers at the interface between the porous media. The dependence of the Nusselt number on the Darcy numbers, Forchheimer coefficients, and particle Reynolds numbers in different parts of the channel is investigated. This study demonstrates that thermal dispersion has a strong effect on the Nusselt number in the channel for large particle Reynolds numbers.

2

Forced convective heat transfer in a parallel-plate channel with a porous core

100%

Kuznetsov A. V.

Applied Mechanics and Engineering

|

1999

|

tom Vol. 4, no 2

271-290

EN

This paper presents an analytical study of the fully developed forced convection in a parallel-plate channel. The central part of the channel is occupied by a porous core and the peripheral part of the channel is occupied by a clear fluid. A uniform heat flux is imposed at the walls of the channel. The Brinkman-Forchheimer-extended Darcy equation is utilized as a momentum equation in the porous region. This formulation accounts for both viscous and quadratic drag effects in the porous region. Analytical solutions for the velocity and temperature distributions, as well as for the Nusselt number are obtained.

3

Limitation of the single-domain numerical approach: Comparisons of analytical and numerical solutions for a forced convection heat transfer problem in a composite duct

100%

Kuznetsov A. V.

Computer Assisted Mechanics and Engineering Sciences

|

2003

|

tom Vol. 10, No. 1

34-43

EN

The aim of this paper is to establish the bounds of applicability of the single-domain numerical approach for computations of convection in composite porous/fluid domains. The large number of papers that have utilized this numerical approach motivates this research. The popularity of this approach is due to the simplicity of its numerical formulation. Since the utilization of the single-domain numerical approach does not require the explicit imposing of any boundary conditions at the porous/fluid interface, the aim of the this research is to investigate whether this method always produces accurate numerical solutions.

4

Computer simulation of fluid flow and heat transfer in strip casting of aluminum alloys

100%

Kuznetsov A. V.

|

tom Vol. 3, no 3

479-490

EN

In this study, results of numerical analysis of the continuous casting process aimed for a production of thin aluminum-copper strips are reported. A characteristic feature of the continuous casting process considered in this paper is a strong forced convection of liquid alloy caused by a changing height of a free surface. Computations are performed for Al-4.5 wt pct Cu alloy. In this investigation, heat transfer process is coupled with the fluid flow which occurs in the liquid metal and in the mushy zone. It is shown that there is an essential forced convection flow in the upper part of mushy zone between the position where the liquidus line reaches the free surface and the position where the height of the free surface reaches its maximum. This flow can cause a destruction of the dendritic structure which in its turn can be one of the reasons for instability of the process.

5

Heat transfer in a turbulent channel flow with a permeable wall

63%

Kuznetsov A. V. , Xiang P.

International Journal of Applied Mechanics and Engineering

|

2006

|

tom Vol. 11, no 3

705-713

EN

A problem of turbulent flow in a channel with a permeable wall recently considered in Hahn and Choi (2002) is extended to include heat transfer. A model is utilized to investigate this problem numerically. The modeling is based on the assumption that the flow in the channel is turbulent while in the porous block the flow remains laminar. The wall functions approach is utilized to determine the boundary conditions for the k and equations. The dependence of the Nusselt number on the Darcy and Reynolds numbers is investigated.

6

Investigation of a laminar flow of a non-Netonian fluid in a helical pipe

63%

Cheng L. , Kuznetsov A. V.

International Journal of Applied Mechanics and Engineering

|

2005

|

tom Vol. 10, no 1

21-37

EN

This paper presents a numerical study of a fully developed laminar flow of a non-Newtonian fluid in a helical pipe. An orthogonal helical coordinate system is utilized and the Navier-Stokes equations for the non-Newtonian fluid in this coordinate system are derived. The SIMPLE algorithm with a staggered grid is adopted to solve the governing equations. The effects of the pressure gradient, the curvature, and the torsion on the fully developed laminar flow in helical pipes are investigated. The comparison of flow dynamics between Newtonian and non-Newtonian fluids is presented.

7

Determination of von Karman's constant using group theoretic methods

51%

Avramenko A. A. , Basok B. I. , Kuznetsov A. V.

International Journal of Applied Mechanics and Engineering

|

2007

|

tom Vol. 12, no 2

329-335

EN

The goal of this research is to obtain a theoretical value of von Karaman's constant from the first principaIs by utilizing renormalization group (RG) results. Fourier decomposition obtained in RG theory of turbulence is considered in the limit of small wavenumbers. Utilizing RG results, a theoretical value of the coefficient in the dissipation rate equation is also obtained.

8

Application of the lie group theory to the analysis of flows in a turbulent boundary layer utilizing different turbulent viscosity models

51%

Avramenko A. A. , Kobzar S. G. , Kuznetsov A. V. , Bowen P. J.

International Journal of Applied Mechanics and Engineering

|

2003

|

tom Vol. 8, no 4

543-557

EN

The properties of symmetry of turbulent boundary layer flows are studied utilizing the Lie group theory. The self-similar forms of the independent variables and the solution functions for the boundary-layer type flows for four models of turbulent viscosity are obtained. The developed approach of finding a self-similar transformation for turbulent boundary-layer problems makes it possible to obtain numerical and simplified analytical solutions for a number of important flow situations.

9

Modeling of atmospheric air pollution by traffic stream in a large industrial center

45%

Lyapkalo A. A. , Dementiev A. A. , Tsurgan A. M. , Kuznetsov A. V. , Ryabchikov V. N.

|

2005

|

tom Nr 13

113-116

10

Current research at HENDES

23%

Trzaska W. H. , Rubchenya V. A. , Aysto J. , Radivojevic Z. , Vakhtine D. N. , Alexandrov A. A. , Evsenin A. , Khlebnikov S. V. , Kuznetsov A. V. , Lyapin V. G. , Ossetrov O. I. , Tiourine G. P. , Alexandrov A. A. , Penionzhkevich Y. E. , Pyatkov Y. V. , Sobolev Y. G. , Mutterer M. , Brinkmann K. , Makarenko V.

|

1998

|

tom Vol. 43, nr 3

291-298

EN

Review of the current research conducted within Finnish-Russian-German collaboration using HENDES detector system is presented together with a brief description of the experimental set-up. The main topics include fusion-fission reactions induced by heavy ions, low energy fission, ternary fission and precise mass distributions in the very asymmetric mass region from proton and deuteron induced fission on uranium and thorium.

PL

W pracy zaprezentowano przegląd aktualnych badań prowadzonych we współpracy fińsko-rosyjsko-niemieckiej przy wykorzystaniu układu detekcyjnego HENDES oraz opisano pokrótce układ eksperymentalny. Wśród głównych tematów wyróżnić można reakcje typu fusion-fission inicjowane przez ciężkie jony, niskoenergetyczne rozszczepienie, rozszczepienie potrójne i dokładne rozkłady mas w obszarze bardzo niesymetrycznych mas w rozszczepieniu uranu i toru inicjowanym przez proton lub deuteron.