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One of the promising technologies for enhanced oil recovery in the development of unconventional oil reservoirs is the thermo-gas method. The method is based on the injection of an oxygen-containing mixture into the formation and its transformation into a highly efficient displacing agent miscible with the formation of oil due to spontaneous in-situ oxidative processes. In some cases, this method has great potential compared to other methods of enhanced oil recovery. This paper discusses some issues of the propagation of in-situ combustion waves. Depending on the parameters of the reservoir and the injected mixture, such waves can propagate in different modes. In this paper, only the direct-flow inverse propagation mode is considered. In this mode, the combustion wave propagates in the direction of the oxidant flow and the reaction front lags behind the heatwave, in which the substance (hydrocarbon fractions, porous skeleton, etc.) is heated to temperatures sufficient for the oxidation reaction to occur. The paper presents the results of an analytical study and numerical simulation of the structure of the inverse wave of in-situ combustion. in two-phase flow in a porous layer. Some simplifying assumptions about the thermal properties of fluid phases was accepted, which allow, on the one hand, to modify the in-situ combustion model observable for analysis, and with another is to convey the main features of this process. The solution of the “running wave” type is considered and the conditions of its implementation are specified. Selected two modes of reaction trailing front regime in-situ combustion waves: hydrodynamic and kinetic. Numerical simulation of the in-situ combustion wave propagation was carried out with using the thermohydrodynamical simulator developed for the numerical integration of non-isothermal multicomponent filtration flows accompanied by phase transitions and chemical reaction.

The paper presents the results of three-dimensional numerical simulation of thermal-hydraulic processes in the Intermediate Heat Exchanger of the advanced Sodium-Cooled Fast-Neutron (BN) Reactor considering a developed methodological approach.

The Intermediate Heat Exchanger (IHX) is located in the reactor vessel and intended to transfer heat from the primary sodium circulating on the shell side to the secondary sodium circulating on the tube side. In case of an integral layout of the primary equipment in the BN reactor, upstream the IHX inlet windows there is a temperature stratification of the coolant due to incomplete mixing of different temperature flows at the core outlet. Inside the IHX, in the area of the input and output windows, a complex longitudinal and transverse flow of the coolant also takes place resulting in an uneven distribution of the coolant flow rate on the tube side and, as a consequence, in an uneven temperature distribution and heat transfer efficiency along the height and radius of the tube bundle.

In order to confirm the thermal-hydraulic parameters of the IHX of the advanced BN reactor applied in the design, a methodological approach for three-dimensional numerical simulation of the heat exchanger located in the reactor vessel was developed, taking into account the three-dimensional sodium flow pattern at the IHX inlet and inside the IHX, as well as justifying the recommendations for simplifying the geometry of the computational model of the IHX.

Numerical simulation of thermal-hydraulic processes in the IHX of the advanced BN reactor was carried out using the FlowVision software package with the standard $k-\varepsilon$ turbulence model and the LMS turbulent heat transfer model.

To increase the representativeness of numerical simulation of the IHX tube bundle, verification calculations of singletube and multi-tube sodium-sodium heat exchangers were performed with the geometric characteristics corresponding to the IHX design.

To determine the input boundary conditions in the IHX model, an additional three-dimensional calculation was performed taking into account the uneven flow pattern in the upper mixing chamber of the reactor.

The IHX computational model was optimized by simplifying spacer belts and selecting a sector model.

As a result of numerical simulation of the IHX, the distributions of the primary sodium velocity and primary and secondary sodium temperature were obtained. Satisfactory agreement of the calculation results with the design data on integral parameters confirmed the adopted design thermal-hydraulic characteristics of the IHX of the advanced BN reactor.

The development of a high-temperature gas-cooled reactor (HTGR) constituting a part of nuclear power-and-process station and intended for large-scale hydrogen production is now in progress in the Russian Federation. One of the key objectives in development of the high-temperature gas-cooled reactor is the computational justification of the accepted design.

The article gives the procedure for the computational analysis of thermal and physical characteristics of the high-temperature gas-cooled reactor. The procedure is based on the use of the state-of-the-art codes for personal computer (PC).

The objective of thermal and physical analysis of the reactor as a whole and of the core in particular was achieved in three stages. The idea of the first stage is to justify the neutron physical characteristics of the block-type core during burn-up with the use of the MCU-HTR code based on the Monte Carlo method. The second and the third stages are intended to study the coolant flow and the temperature condition of the reactor and the core in 3D with the required degree of detailing using the FlowVision and the ANSYS codes.

For the purpose of carrying out the analytical studies the computational models of the reactor flow path and the fuel assembly column were developed.

As per the results of the computational modeling the design of the support columns and the neutron physical characteristics of the fuel assembly were optimized. This results in the reduction of the total hydraulic resistance of the reactor and decrease of the maximum temperature of the fuel elements.

The dependency of the maximum fuel temperature on the value of the power peaking factors determined by the arrangement of the absorber rods and of the compacts of burnable absorber in the fuel assembly is demonstrated.

The study of the structural characteristics of composites and nanostructures is of fundamental importance in materials science. Theoretical and numerical modeling and simulation of the mechanical properties of nanostructures is the main tool that allows for complex studies that are difficult to conduct only experimentally. One example of nanostructures considered in this work are carbon nanotubes (CNTs), which have good thermal and electrical properties, as well as low density and high Young’s modulus, making them the most suitable reinforcement element for composites, for potential applications in aerospace, automotive, metallurgical and biomedical industries. In this review, we reviewed the modeling methods, mechanical properties, and applications of CNT-reinforced metal matrix composites. Some modeling methods applicable in the study of composites with polymer and metal matrices are also considered. Methods such as the gradient descent method, the Monte Carlo method, methods of molecular statics and molecular dynamics are considered. Molecular dynamics simulations have been shown to be excellent for creating various composite material systems and studying the properties of metal matrix composites reinforced with carbon nanomaterials under various conditions. This paper briefly presents the most commonly used potentials that describe the interactions of composite modeling systems. The correct choice of interaction potentials between parts of composites directly affects the description of the phenomenon being studied. The dependence of the mechanical properties of composites on the volume fraction of the diameter, orientation, and number of CNTs is detailed and discussed. It has been shown that the volume fraction of carbon nanotubes has a significant effect on the tensile strength and Young’s modulus. The CNT diameter has a greater impact on the tensile strength than on the elastic modulus. An example of works is also given in which the effect of CNT length on the mechanical properties of composites is studied. In conclusion, we offer perspectives on the direction of development of molecular dynamics modeling in relation to metal matrix composites reinforced with carbon nanomaterials.

The article is dedicated to mathematic modeling of natural water desalination process by method of thermal distillation. The article gives the equations which allow describing the processes of film flowing and boiling of water, steam condensation and vacuum maintenance. The article presents the algorithm of calculation, implemented in MatLab computer mathematic system and Excel electronic tables, and the initial data required for the calculation. The model has been checked for adequacy. The calculation of ten-effect distillation system is given. The results of work can be used in design and optimization of process conditions for distillation systems.

The article is devoted to the numerical study of shock-wave flows in inhomogeneous media–gas mixtures. In this work, a two-speed two-temperature model is used, in which the dispersed component of the mixture has its own speed and temperature. To describe the change in the concentration of the dispersed component, the equation of conservation of “average density” is solved. This study took into account interphase thermal interaction and interphase pulse exchange. The mathematical model allows the carrier component of the mixture to be described as a viscous, compressible and heat-conducting medium. The system of equations was solved using the explicit Mac-Cormack second-order finite-difference method. To obtain a monotone numerical solution, a nonlinear correction scheme was applied to the grid function. In the problem of shock-wave flow, the Dirichlet boundary conditions were specified for the velocity components, and the Neumann boundary conditions were specified for the other unknown functions. In numerical calculations, in order to reveal the dependence of the dynamics of the entire mixture on the properties of the solid component, various parameters of the dispersed phase were considered — the volume content as well as the linear size of the dispersed inclusions. The goal of the research was to determine how the properties of solid inclusions affect the parameters of the dynamics of the carrier medium — gas. The motion of an inhomogeneous medium in a shock duct divided into two parts was studied, the gas pressure in one of the channel compartments is more important than in the other. The article simulated the movement of a direct shock wave from a high-pressure chamber to a low–pressure chamber filled with a dusty medium and the subsequent reflection of a shock wave from a solid surface. An analysis of numerical calculations showed that a decrease in the linear particle size of the gas suspension and an increase in the physical density of the material from which the particles are composed leads to the formation of a more intense reflected shock wave with a higher temperature and gas density, as well as a lower speed of movement of the reflected disturbance reflected wave.

Magnetic systems, in which due to competition between the direct Heisenberg exchange and the Dzyaloshinskii –Moriya interaction, magnetic vortex structures — skyrmions appear, were studied using the Metropolis algorithm.

The conditions for the nucleation and stable existence of magnetic skyrmions in two-dimensional magnetic films in the frame of the classical Heisenberg model were considered in the article. A thermal stability of skyrmions in a magnetic film was studied. The processes of the formation of various states in the system at different values of external magnetic fields were considered, various phases into which the Heisenberg spin system passes were recognized. The authors identified seven phases: paramagnetic, spiral, labyrinth, spiralskyrmion, skyrmion, skyrmion-ferromagnetic and ferromagnetic phases, a detailed analysis of the configurations is given in the article.

Two phase diagrams were plotted: the first diagram shows the behavior of the system at a constant $D$ depending on the values of the external magnetic field and temperature $(T, B)$, the second one shows the change of the system configurations at a constant temperature $T$ depending on the magnitude of the Dzyaloshinskii – Moriya interaction and external magnetic field: $(D, B)$.

The data from these numerical experiments will be used in further studies to determine the model parameters of the system for the formation of a stable skyrmion state and to develop methods for controlling skyrmions in a magnetic film.

The viscoelastic fluid flow model across a porous medium has captivated the interest of many contemporary researchers due to its industrial and technical uses, such as food processing, paper and textile coating, packed bed reactors, the cooling effect of transpiration and the dispersion of pollutants through aquifers. This article focuses on the influence of variable viscosity and viscoelasticity on the magnetohydrodynamic oscillatory flow of second-order fluid through thermally radiating wavy walls. A mathematical model for this fluid flow, including governing equations and boundary conditions, is developed using the usual Boussinesq approximation. The governing equations are transformed into a system of nonlinear ordinary differential equations using non-similarity transformations. The numerical results obtained by applying finite-difference code based on the Lobatto IIIa formula generated by bvp4c solver are compared to the semi-analytical solutions for the velocity, temperature and concentration profiles obtained using the homotopy perturbation method (HPM). The effect of flow parameters on velocity, temperature, concentration profiles, skin friction coefficient, heat and mass transfer rate, and skin friction coefficient is examined and illustrated graphically. The physical parameters governing the fluid flow profoundly affected the resultant flow profiles except in a few cases. By using the slope linear regression method, the importance of considering the viscosity variation parameter and its interaction with the Lorentz force in determining the velocity behavior of the viscoelastic fluid model is highlighted. The percentage increase in the velocity profile of the viscoelastic model has been calculated for different ranges of viscosity variation parameters. Finally, the results are validated numerically for the skin friction coefficient and Nusselt number profiles.

Study of work of heating equipment is an actual issue because it allows determining optimal regimes to reach highest efficiency. At that it is very helpful to use computer simulation to predict how different heating modes influence the effectiveness of the heating process and wear of heating equipment. Computer simulation provides results whose accuracy is proven by many studies and requires costs and time less than real experiments. In terms of present research, computer simulation of heating of air tuyere of blast furnace was realized with the help of FEM software. Background studies revealed possibility to simulate it as a flat, axisymmetric problem and DEFORM-2D software was used for simulation. Geometry, necessary for simulation, was designed with the help of SolidWorks, saved in .dxf format. Then it was exported to DEFORM-2D pre-processor and positioned. Preliminary and boundary conditions were set up. Several modes of operating regimes were under analysis. In order to demonstrate influence of eah of the modes and for better visualization point tracking option of the DEFORM-2D post-processor was applied. Influence of thermal insulation box plugged into blow channel, with and without air gap, and thermal coating on air tuyere’s temperature field was investigated. Simulation data demonstrated significant effect of thermal insulation box on air tuyere’s temperature field. Designed model allowed to simulate tuyere’s burnout as a result of interaction with liquid iron. Conducted researches have demonstrated DEFORM-2D effectiveness while using it for simulation of heat transfer and heating processes. DEFORM-2D is about to be used in further studies dedicated to more complex process connected with temperature field of blast furnace’s air tuyere.

This work is devoted to molecular dynamic modeling of the thermal impact processes on the metal sample consisting of nickel atoms. For the solution of this problem, a continuous mathematical model on the basis of the classical Newton mechanics equations has been used; a numerical method based on the Verlet scheme has been chosen; a parallel algorithm has been offered, and its realization within the MPI and OpenMP technologies has been executed. By means of the developed parallel program, the investigation of thermodynamic equilibrium of nickel atoms’ system under the conditions of heating a sample to desired temperature has been executed. In numerical experiments both optimum parameters of calculation procedure and physical parameters of analyzed process have been defined. The obtained numerical results are well corresponding to known theoretical and experimental data.