Some classes of nonstationary equations with growing lower terms

1998 ◽  
Vol 39 (4) ◽  
pp. 755-764 ◽  
Author(s):  
A. I. Kozhanov
Keyword(s):  
Nonstationary Equations

A new method for solving nonlinear nonstationary equations (case of one space variable)

1982 ◽  
Vol 31 (2) ◽  
pp. 110-114
Author(s):  
Yu. I. Kazantsev
Keyword(s):  
Space Variable ◽  
New Method ◽  
Nonstationary Equations

Shaping the Combustion Chamber of a Piston Engine with Direct Injection of Gasoline

2019 ◽  
pp. 67-76
Author(s):  
R.Z. Kavtaradze ◽  
A.A. Kasko ◽  
A.A. Zelentsov
Keyword(s):  
Combustion Chamber ◽  
Direct Injection ◽  
Combustion Process ◽  
Three Dimensional ◽  
Numerical Control ◽  
Engine Operation ◽  
Model Fuel ◽  
Nonstationary Equations ◽  
Current Lines ◽  
Control Volumes

The object of the study was a six-cylinder in-line engine for land transport system with direct gasoline supply and forced ignition. The problem of shaping the combustion chamber is solved using the numerical control volumes method in a three-dimensional formulation. Nonstationary equations of energy, motion, diffusion and continuity in the Reynolds form, supplemented by the k-ζ-f model of turbulence, are used as a basis for modelling the engine operation. To model fuel combustion, an extended coherent flame model (ECFM) was used. Calculations were performed using the AVL FIRE software. The processes of mixture formation were optimized by considering the current lines and velocity fields of a moving charge, taking into account the geometry of the combustion chamber and intake and exhaust ports. As a result, the efficiency of the engine increased and the combustion process became more stable in the part load modes employing different fuel supply laws.

scholarly journals Nonstationary Equations for the Reaction Layer with the Degenerate Equilibrium Points

2017 ◽  
Vol 24 (3) ◽  
pp. 309-321
Author(s):  
Aleksei A. Bykov ◽  
Kristina E. Ermakova
Keyword(s):  
Reaction Layer ◽  
Equilibrium Points ◽  
Degenerate Equilibrium ◽  
Nonstationary Equations

AVERAGING THE NONSTATIONARY EQUATIONS OF VISCOUS SUBSTANCE FILTRATION THROUGH A RIGID POROUS MEDIUM

2014 ◽  
Vol 5 (1) ◽  
pp. 35-61
Author(s):  
Viktoria L. Savatorova ◽  
A. V. Talonov ◽  
A. N. Vlasov ◽  
D. B. Volkov-Bogorodsky
Keyword(s):  
Porous Medium ◽  
Nonstationary Equations ◽  
Viscous Substance

INVARIANT DIFFERENCE SCHEMES FOR PARABOLIC EQUATIONS WITH TRANSFORMATIONS OF INDEPENDENT VARIABLES

1999 ◽  
Vol 09 (01) ◽  
pp. 93-110 ◽  
Author(s):  
A. A. SAMARSKII ◽  
V. I. MAZHUKIN ◽  
P. P. MATUS ◽  
V. G. RYCHAGOV ◽  
I. SMUROV
Keyword(s):  
Parabolic Equations ◽  
A Priori Estimates ◽  
Order Approximation ◽  
A Priori ◽  
Parabolic Type ◽  
Difference Schemes ◽  
Invariance Property ◽  
Independent Variables ◽  
Priori Estimates ◽  
Nonstationary Equations

In this paper, invariant difference schemes for nonstationary equations under independent variables transformation constructed and investigated. Under invariance of difference scheme we mean its ability to preserve basic properties (stability, approximation, convergency, etc.) in various coordinate systems. Difference schemes of the second-order approximation that satisfy the invariance property are constructed for equations of parabolic type. Stability and convergency investigation of correspondent difference problems are carried out; a priori estimates in various grid norms are obtained.

New Two-Fluid Turbulence Model Based Numerical Simulation of Flow in a Flat Suddenly Expanding Channel

2021 ◽  
pp. 24-39
Author(s):  
Z.M. Malikov ◽  
M.E. Madaliev
Keyword(s):  
Turbulence Model ◽  
Control Volume ◽  
Difference Approximation ◽  
Flat Channel ◽  
Central Difference ◽  
Fluid Turbulence ◽  
Before And After ◽  
Nonstationary Equations ◽  
The Difference ◽  
Two Fluid

The purpose of the research was to numerically study the structure of the flow in a flat channel in the zone of its sudden step-like expansion. The results of the study are given in the paper. The calculations are carried out with the use of a new two-fluid turbulence model and are based on the numerical solution of a system of nonstationary equations. The profiles of axial velocity and turbulent stress in various sections of the channel before and after the step were obtained, as well as the dependence of the friction coefficient for the lower wall of the channel on the distance after the step. For the difference approximation of the initial equations, the control volume approach was applied; the relationship between the velocities and pressure was found using the SIMPLEC procedure. Meanwhile, the viscosity terms were approximated by the central difference, and for the convective terms the QUICK second-order accuracy scheme was used. To confirm the correctness of the numerical results, we compared them with the experimental data taken from the NASA database for the Reynolds number Re = 36,000. The results obtained using the SA and SST models are also given in the paper. Despite the coarse grid used for numerical calculations, the results based on the new two-fluid turbulence model are not less accurate than the results determined by the RANS models for predicting separated flows in the flat channel in the zone of its sudden backward-facing step expansion

Error estimates for projection-difference schemes for degenerate nonstationary equations

2006 ◽  
Vol 42 (7) ◽  
pp. 1013-1017
Author(s):  
A. D. Lyashko ◽  
E. M. Fedotov
Keyword(s):  
Error Estimates ◽  
Difference Schemes ◽  
Nonstationary Equations
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