Yu. D. Shevelev

Non‐Equilibrium Supersonic CO2 Flows with Real Gas Effects near a Blunt Body

The paper deals with the numerical simulation of a supersonic viscous flow containing CO2 molecules near a space body entering the Mars atmosphere. The gas dynamic equations in a shock layer are coupled to the equations of vibrational and chemical kinetics in the mixture CO2/CO/O2/C/O using three theoretical models for CO2 vibrational excitation. Three‐temperature and two‐temperature non‐equilibrium approaches as well as the one‐temperature thermal equilibrium model have been applied. A comparison of gas flow parameters and heat transfer calculated on the basis of different approximations is presented, and the effect of CO2 vibrational non‐equilibrium is discussed. Transport coefficients in a flow are computed using rigorous kinetic theory algorithms which have been incorporated directly to the numerical schemes. The effect of bulk viscosity in a shock layer is studied.

Numerical simulation of hypersonic flows around space vehicles descending in the Martian atmosphere

The hypersonic flow near a space vehicle in the Martian atmosphere is studied. The flow around vehicles is considered within the model of a viscous shock layer. The effect of chemical reactions, nonequilibrium excitation of internal molecular degrees of freedom and multicomponent diffusion on the flow parameters and the heat flux to the surface of the spacecraft is investigated.

Non‐Equilibrium Kinetics and Transport Processes in a Hypersonic Flow of CO2/CO/O2/C/O Mixture

In this paper, non‐equilibrium kinetics and transport processes in a viscous hypersonic flow of reacting CO2/CO/O2/C/O mixture are studied on the basis of the kinetic theory methods. Vibrational excitation of CO2, CO and O2 molecules as well as non‐equilibrium dissociation, recombination and exchange reactions are taken into account and the influence of non‐equilibrium kinetics on transport properties is studied. A five‐temperature model for a non‐equilibrium flow suitable for applications is derived from the kinetic theory and used for the evaluation of transport properties of considered mixture under re‐entry conditions. The paper presents the closed set of non‐equilibrium flow equations, expressions for transport properties and results of calculations.

Numerical solution of the problem of the theory of point explosion in Lagrangian coordinates. Some new results

An unsteady problem of the point explosion theory in Lagrangian coordinates is considered. The process of reorganization of gas flow in the area captured by blast-wave is investigated. During a numerical experiment, by variation of nondimensional governing parameters of the problem, the features of such a flow are revealed for the first time. It is discovered that, except for the nodal point singularity in the center of energy release, determined by the initial conditions of the problem (L.I. Sedov’s self-similar solution), extra singular focus, saddle, and node points are formed in the disturbed flow area over time.

The influence of CO2 kinetics on the hypersonic flow near blunt bodies

In this paper, the influence of non-equilibrium CO2 kinetics on gas dynamic parameters and transport properties in a viscous shock layer near blunt bodies is studied. This problem is important for accurate prediction of macroscopic parameters and heat transfer near a space vehicle re-entering the Mars atmosphere. The hypersonic flow of reacting CO2/CO/O2/C/O mixture is studied numerically using the accurate kinetic theory models for transport properties and chemical reaction rates proposed in our previous papers on the basis of three-temperature vibrational distributions. The kinetic theory algorithms were implemented directly to the computational fluid dynamics solvers. The transport properties and gas dynamic parameters in 2-D viscous shock layer near blunt bodies of different shape are studied for various test cases under Mars re-entry conditions. The influence of non-equilibrium effects on gas flow parameters and heat transfer is discussed; a quite different structure of a shock layer is found for various body shapes. The comparison with the results obtained using more simple models for CO2 kinetics, transport coefficients, and reaction rates is shown.In this paper, the influence of non-equilibrium CO2 kinetics on gas dynamic parameters and transport properties in a viscous shock layer near blunt bodies is studied. This problem is important for accurate prediction of macroscopic parameters and heat transfer near a space vehicle re-entering the Mars atmosphere. The hypersonic flow of reacting CO2/CO/O2/C/O mixture is studied numerically using the accurate kinetic theory models for transport properties and chemical reaction rates proposed in our previous papers on the basis of three-temperature vibrational distributions. The kinetic theory algorithms were implemented directly to the computational fluid dynamics solvers. The transport properties and gas dynamic parameters in 2-D viscous shock layer near blunt bodies of different shape are studied for various test cases under Mars re-entry conditions. The influence of non-equilibrium effects on gas flow parameters and heat transfer is discussed; a quite different structure of a shock layer is found for var...

The effect of multicomponent diffusion on supersonic flow of carbon dioxide past bodies

Different approaches are considered to the inclusion of multicomponent diffusion into numerical analysis of supersonic flow of carbon dioxide past blunt-nosed bodies. Calculation results are given, which illustrate the effect of diffusion processes on heat transfer to the surface of a space vehicle moving in the atmosphere of Mars.

Destruction mechanisms of meteoroids and heat transfer to their surfaces

The phenomena of the movement and destruction of celestial bodies in the Earth’s atmosphere are investigated based on the advanced equations of meteor physics. The movement of meteorites in Kunya-Urgench (1998) and Chelyabinsk (2013) is analyzed as an example taking into account changes in the ablation along the trajectory. Different mechanisms of destruction of these meteorites are described.

Numerical investigation of interactions of multiple spherical shock waves between themselves and with the underlying surface

Within the investigation of various aspects of asteroid and comet danger and, in particular, the explosion of several fragments of meteoroids in the atmosphere above the Earth surface, the toy problem about four point explosions in the case of their special arrangement above the underlying surface is numerically solved. Complex interactions of primary and secondary shock waves between themselves, with the hard surface, and with tangential discontinuities are examined. The structure of flow inside gas regions disturbed by the explosions—the occurrence of eddy structures in them and the influence of reflected shocks waves on them—are investigated. The tendency of the external wave fronts of each explosion to form a unified front and the tendency of their internal hot domains to merge into a joined configuration (where the second process proceeds a little later than the first one) is revealed. This unified front and joined configuration are qualitatively identical to the external internal structure for the solitary explosion. The specially arranged explosions are chosen because the effects of multiple diffraction, interference, and, the main thing, cumulation of spherical waves are manifested more clearly in this caseTwo variants with different altitude of the explosions above the surface are calculated.

Development of mathematical models and numerical methods for aerodynamic design on multiprocessor computers

Complex-geometry design and grid generation are addressed. The gasdynamic equations are solved, and the numerical results are compared with experimental data. For aerodynamic problems, a suite of mathematical and information technology tools is proposed for the support and management of geometric models of actual objects. Based on the mathematical modeling methods developed, numerical experiments can be performed for a wide class of geometric forms and the aerodynamic properties of aircraft can be predicted with allowance for the viscosity effects.

Last achievements and some trends in CFD

Computational fluid dynamics combine the basic concepts of modern fluid mechanics, numerical methods, software with the last achievements in hardware. This chapter considers the last attempts in numerical simulation flows past “real” geometries. For this purpose it is necessary to design the appropriate geometry, to choose the coordinate systems correctly, to provide adequate mathematical model of an initial value problem, to approximate the governing differential equations by numerical ones, to design the numerical algorithm, to realize the program on the computer, to visualize the flow field, and to establish feedback of obtained results with the ones from the experiment and the list continues. The working approach provides a technique to design the grid compatible with the numerical method. The method provides an opportunity to separate theory from coding. The chapter summarizes the recent progress of researchers with numerical modeling of 3D (3D) inviscous and viscous gas flow. The approach is based on the tensor form and invariant approximations for governing differential equations. From computational point of view, it means that for arbitrary coordinate systems and different geometry the same algorithms can be used. It also describes some of the researches in model development being carried out. Finally, the chapter displays some of the applications of the codes particularly to flows past prototypes of space vehicle geometry.