Alexey Kudryavtsev | Institute for Philosophy and Law of the Siberian Branch of the Russian Academy of Sciences (original) (raw)
Papers by Alexey Kudryavtsev
Siberian Journal of Physics, 2008
Investigations of a receptivity and disturbances evolution generated in a hypersonic shock layer ... more Investigations of a receptivity and disturbances evolution generated in a hypersonic shock layer on a flat plate under the action of disturbances of the external flow and disturbances, entered in a shock layer locally on the surface of the plate model is represented in work
Monthly Notices of the Royal Astronomical Society, 2019
ABSTRACTLarge-scale instability of gravitating systems plays a key role in collisionless relaxati... more ABSTRACTLarge-scale instability of gravitating systems plays a key role in collisionless relaxation and in reaching a quasi-stationary state at the early stage of evolution. Advanced high-resolution methods and permanently increasing performance of computational systems allow this phenomenon to be studied by means of computer simulations at a new level. In this paper, an approach to verification and validation of computer codes implementing high-resolution methods is proposed. The approach is based on comparisons of the simulation results with exact non-stationary solutions of the Vlasov–Poisson equations. The evolution of the gravitating layer model is considered as an example of implementation of this approach. A one-parameter family of exact models of a non-stationary gravitating layer is described, and their stability to large-scale disturbances in the linear approximation is analytically studied. Non-linear instability development is computed with the use of the fifth-order con...
AIP Conference Proceedings, 2016
The present paper describes HyCFS code, developed for numerical simulation of compressible high-s... more The present paper describes HyCFS code, developed for numerical simulation of compressible high-speed flows on hybrid CPU/GPU (Central Processing Unit / Graphical Processing Unit) computational clusters on the basis of full unsteady Navier-Stokes equations, using modern shock capturing high-order TVD (Total Variation Diminishing) and WENO (Weighted Essentially Non-Oscillatory) schemes on general curvilinear structured grids. We discuss the specific features of hybrid architecture and details of program implementation and present the results of code verification.
Very high energy release rates, which can be achieved in detonations, for many years attract atte... more Very high energy release rates, which can be achieved in detonations, for many years attract attention of engineers to possible practical applications of this phenomenon. As was shown for the first time by Ya. B. Zel’dovich [1], the detonation regime of combustion is also more efficient thermodynamically than the deflagration under the same initial conditions. One can hope that development of detonation-based fuel-burning devices will eventually lead to the design of more cost-effective and compact engines for of sub-orbital spacecraft and other high-speed vehicles. In recent years, significant efforts were undertaken for a detailed research on the concept of Pulse Detonation Engine (PDE), a device which creates propulsion by burning the fuel in a combustion chamber where a traveling detonation wave is periodically initiated. Nevertheless, it seems that, owing to the difficulties of fast exhaust of the combustion products and recharging of the combustion chamber by the fresh fuel mixture, the current generation PDEs are not yet capable of running at high frequencies needed for efficiency. There are a few alternative concepts of detonation-based engines. In particular, a promising idea that can be traced back to the work of B. V. Voitsekhovskii [2] is to use a detonation wave spinning in an annular tube, which is constantly refilled by a combustible mixture from one end. It is the so-called Continuous Detonation Wave Engine (CDWE), which was mostly studied in the Lavrent’yev Instutute of Hydrodynamics, Novosibirsk, Russia. In many aspects, CDWE is close to PDE operating at very high frequency (several kHz). For a review of this concept and its comparison with PDE, see the recent publications [3,4]. In the present work, the detonation wave propagation in CDWE is simulated numerically by solving the Euler equations for a chemically reacting flow. A detailed chemical model (6 species, 7 reactions) is used to describe the combustion of stoichiometric hydrogen-oxygen mixture. The governing equations are solved with a highresolution shock-capturing WENO (weighted essentially non-oscillatory) scheme. The numerical simulations are used to obtain a clear picture of processes in the combustion chamber of CDWE, elucidate the underlying physical mechanisms, and investigate the influence of different parameters on this phenomenon.
arXiv (Cornell University), Jun 16, 2017
A generalized notion of a nonlocal tensor order parameter is introduced within the framework of t... more A generalized notion of a nonlocal tensor order parameter is introduced within the framework of the phenomenological approach. This parameter has the form of a traceless tensor correlation function or a tensor integral operator. Based on this form, the governing relations are written, which determine the steady states and phase transitions of the deformed liquid crystal. Linear relations for eigenfunctions of the introduced operator are derived. A principal drawback of currently available models of liquid crystals based on the local presentation of the tensor order parameter (equality of two Frank constants in the case of a quadratic form of the strain part of the free energy) is eliminated. Particular examples are considered, which demonstrate the model workability and the absence of contradictions in the model as well as its adequacy when describing small-scale structures.
Nucleation and Atmospheric Aerosols, 2023
ACTUAL PROBLEMS OF CONTINUUM MECHANICS: EXPERIMENT, THEORY, AND APPLICATIONS
Numerical simulation of the Rayleigh-Taylor instability in a plain layer of argon over a layer of... more Numerical simulation of the Rayleigh-Taylor instability in a plain layer of argon over a layer of helium in a field of gravitational force was performed using continuum and kinetic approaches. Continuum model is based on the Navier-Stokes equations for a gas mixture, kinetic approach is on the Direct Simulation Monte Carlo method. The onset of large-scale movement and mixing processes are investigated. Quantitative characteristics of the evolution of the Rayleigh-Taylor instability in a rarefied mode are obtained.
Combustion, Explosion, and Shock Waves, 2021
AIP Conference Proceedings, 2021
The effects of the surface undulation on the development of boundary layer instabilities are stud... more The effects of the surface undulation on the development of boundary layer instabilities are studied in the supersonic boundary layer. The direct numerical simulations are performed for the boundary layer on a flat plate at flow Mach number M = 6. The surface undulation is considered as the means of passive flow control of the laminar-turbulent transition. It has been found that a wavy portion of the surface located at some distance from the leading edge can significantly reduce the amplitude of fluctuations downstream. The effect of suppressing disturbances significantly increases with increasing both the number of waves on the surface (i.e., the length of the wavy portion), and their depth.
The results of numerical simulations of the propagation of the shock wave in a cylindrical shock ... more The results of numerical simulations of the propagation of the shock wave in a cylindrical shock tube of large length are presented. The results of the numerical computations agree well with the experimental data of Duff. The effects of viscous friction and heat conduction cause significant difference of the shock wave velocity from its inviscid theoretical value. The results of the computations at the considered flow parameters show that the shock wave and the contact surface, starting from a certain moment of time, propagate with equal speeds.
AIP Conference Proceedings, 2017
There are various methods for calculating rarefied gas flows, in particular, statistical methods ... more There are various methods for calculating rarefied gas flows, in particular, statistical methods and deterministic methods based on the finite-difference solutions of the Boltzmann nonlinear kinetic equation and on the solutions of model kinetic equations. There is no universal method; each has its disadvantages in terms of efficiency or accuracy. The choice of the method depends on the problem to be solved and on parameters of calculated flows. Qualitative theoretical arguments help to determine the range of parameters of effectively solved problems for each method; however, it is advisable to perform comparative tests of calculations of the classical problems performed by different methods and with different parameters to have quantitative confirmation of this reasoning. The paper provides the results of the calculations performed by the authors with the help of the Direct Simulation Monte Carlo method and finite-difference methods of solving the Boltzmann equation and model kinetic equations. Based on this comparison, conclusions are made on selecting a particular method for flow simulations in various ranges of flow parameters.
HIGH-ENERGY PROCESSES IN CONDENSED MATTER (HEPCM 2019): Proceedings of the XXVI Conference on High-Energy Processes in Condensed Matter, dedicated to the 150th anniversary of the birth of S.A. Chaplygin, 2019
Development of unstable two-dimensional and three-dimensional disturbances of various modes in th... more Development of unstable two-dimensional and three-dimensional disturbances of various modes in the boundary layer on the flat part of the model and their influence on the flow separation zone and the flow in the reattachment area on the compression ramp are studied with the direct numerical simulation. A supersonic flow with the flow Mach number M = 5.373 on a compression ramp with an angle of 5.5 degrees is simulated. The calculations are carried out using the CFD code HyCFS developed at the Laboratory of Computational Aerodynamics of the Institute of Theoretical and Applied Mechanics for solving the Navier-Stokes equations on hybrid-architecture computer clusters using graphical processing units. Based on the results of the numerical simulations data on the mean and nonstationary characteristics of the separated flow and surface characteristics in the vicinity of the boundary layer reattachment point have been obtained. The effect of developing large-scale turbulent structures in the transitional boundary layer on the fluctuations of the separation zone is studied, and the dynamics of critical parameters of the flow near the reattachment point is studied in detail. The calculation results show significant effect of the initial amplitudes of disturbances on the flow dynamics in the separation zone and the size of the zone. For sufficiently large amplitudes, laminar-turbulent transition occurs on the compression ramp.
AIP Conference Proceedings, 2017
Numerical simulation of detonation propagation in a plane channel with detailed chemical mechanis... more Numerical simulation of detonation propagation in a plane channel with detailed chemical mechanisms on supercomputers with GPUs
AIP Conference Proceedings, 2017
The results of three-dimensional numerical simulations of the interaction of the plane N-wave pro... more The results of three-dimensional numerical simulations of the interaction of the plane N-wave propagating at an angle to the free stream in the transverse direction with the sharp and blunted leading edges of the plate in a supersonic flow are presented. Interaction of the N-wave with a weak shock attached to the leading edge of the sharp plate causes corrugation of the shock wave surface that propagates downstream. A steady pressure perturbation is also formed that propagates inside the boundary layer in the transverse direction at an angle close to the Mach angle. This perturbation causes curving of the streamlines in the boundary layer and generation of a quasi-steady vorticity disturbance. In the case of the N-wave impinging on the leading edge of the blunted plate there is a large subsonic zone behind the bow shock where the pronounced oblique directivity of the disturbance transmitted through the shock is declined. Nevertheless, local disturbances of the flow parameters are observed in the boundary layer downstream of the region of the contact of the oblique shocks of the N-wave with the bow shock.
AIP Conference Proceedings, 2018
The effects of the surface roughness on mean flow distortion and generation of flow instabilities... more The effects of the surface roughness on mean flow distortion and generation of flow instabilities in a supersonic boundary layer on a blunted cone at flow Mach number 5.95 are studied with the direct numerical simulation. The considered cases include randomly distributed roughness, single roughness element, surface roughness combined with periodic blowing/suction disturbance, interaction of the group of roughness elements. Geometrical and dynamical conditions leading to the formation of intensive streamwise vortices downstream the roughness elements, growth of flow fluctuations in these vortices, and laminar-turbulent transition are discussed.
The numerical simulation of the unsteady effects in the interaction of an incident shock wave wit... more The numerical simulation of the unsteady effects in the interaction of an incident shock wave with the transitional flat-plate supersonic boundary layer has been performed. The Mach 2 supersonic boundary layer excited by unstable disturbances in the form of linear stability waves undergoes laminar-turbulent transition. An incident oblique shock wave impinges on the transitional boundary layer thus causing boundary layer separation. Large-scale turbulence structures evolving in the transitional boundary layer cause significant flow oscillations in the shock wave / boundary layer interaction region which manifests in fluctuations of the position and shape of the separation and reattachment lines, and also in staggering of the reflected shock wave.
AIP Conference Proceedings, 2008
Numerical simulations of shock wave propagation in microchannels and microtubes (viscous shock tu... more Numerical simulations of shock wave propagation in microchannels and microtubes (viscous shock tube problem) have been performed using three different approaches: the Navier-Stokes equations with the velocity slip and temperature jump boundary conditions, the statistical Direct Simulation Monte Carlo method for the Boltzmann equation, and the model kinetic Bhatnagar-Gross-Krook equation with the Shakhov equilibrium distribution function. Effects of flow rarefaction and dissipation are investigated and the results obtained with different approaches are compared. A parametric study of the problem for different Knudsen numbers and initial shock strengths is carried out using the Navier-Stokes computations.
AIP Conference Proceedings, 2011
TsAGI Science Journal, 2010
AIP Conference Proceedings, 2016
The effects of the distributed surface roughness on mean flow distortion and generation of flow i... more The effects of the distributed surface roughness on mean flow distortion and generation of flow instabilities in a supersonic boundary layer at Mach number 2 are studied with the direct numerical simulation. Roughness elements cause distortions of the mean flow field and flow unsteadiness in their wake. Farther downstream, growth of the fluctuations contained in the streamwise vortices and the interaction of the adjacent vortices lead to a breakup of the boundary layer manifesting the beginning of the laminar–turbulent transition.
Siberian Journal of Physics, 2008
Investigations of a receptivity and disturbances evolution generated in a hypersonic shock layer ... more Investigations of a receptivity and disturbances evolution generated in a hypersonic shock layer on a flat plate under the action of disturbances of the external flow and disturbances, entered in a shock layer locally on the surface of the plate model is represented in work
Monthly Notices of the Royal Astronomical Society, 2019
ABSTRACTLarge-scale instability of gravitating systems plays a key role in collisionless relaxati... more ABSTRACTLarge-scale instability of gravitating systems plays a key role in collisionless relaxation and in reaching a quasi-stationary state at the early stage of evolution. Advanced high-resolution methods and permanently increasing performance of computational systems allow this phenomenon to be studied by means of computer simulations at a new level. In this paper, an approach to verification and validation of computer codes implementing high-resolution methods is proposed. The approach is based on comparisons of the simulation results with exact non-stationary solutions of the Vlasov–Poisson equations. The evolution of the gravitating layer model is considered as an example of implementation of this approach. A one-parameter family of exact models of a non-stationary gravitating layer is described, and their stability to large-scale disturbances in the linear approximation is analytically studied. Non-linear instability development is computed with the use of the fifth-order con...
AIP Conference Proceedings, 2016
The present paper describes HyCFS code, developed for numerical simulation of compressible high-s... more The present paper describes HyCFS code, developed for numerical simulation of compressible high-speed flows on hybrid CPU/GPU (Central Processing Unit / Graphical Processing Unit) computational clusters on the basis of full unsteady Navier-Stokes equations, using modern shock capturing high-order TVD (Total Variation Diminishing) and WENO (Weighted Essentially Non-Oscillatory) schemes on general curvilinear structured grids. We discuss the specific features of hybrid architecture and details of program implementation and present the results of code verification.
Very high energy release rates, which can be achieved in detonations, for many years attract atte... more Very high energy release rates, which can be achieved in detonations, for many years attract attention of engineers to possible practical applications of this phenomenon. As was shown for the first time by Ya. B. Zel’dovich [1], the detonation regime of combustion is also more efficient thermodynamically than the deflagration under the same initial conditions. One can hope that development of detonation-based fuel-burning devices will eventually lead to the design of more cost-effective and compact engines for of sub-orbital spacecraft and other high-speed vehicles. In recent years, significant efforts were undertaken for a detailed research on the concept of Pulse Detonation Engine (PDE), a device which creates propulsion by burning the fuel in a combustion chamber where a traveling detonation wave is periodically initiated. Nevertheless, it seems that, owing to the difficulties of fast exhaust of the combustion products and recharging of the combustion chamber by the fresh fuel mixture, the current generation PDEs are not yet capable of running at high frequencies needed for efficiency. There are a few alternative concepts of detonation-based engines. In particular, a promising idea that can be traced back to the work of B. V. Voitsekhovskii [2] is to use a detonation wave spinning in an annular tube, which is constantly refilled by a combustible mixture from one end. It is the so-called Continuous Detonation Wave Engine (CDWE), which was mostly studied in the Lavrent’yev Instutute of Hydrodynamics, Novosibirsk, Russia. In many aspects, CDWE is close to PDE operating at very high frequency (several kHz). For a review of this concept and its comparison with PDE, see the recent publications [3,4]. In the present work, the detonation wave propagation in CDWE is simulated numerically by solving the Euler equations for a chemically reacting flow. A detailed chemical model (6 species, 7 reactions) is used to describe the combustion of stoichiometric hydrogen-oxygen mixture. The governing equations are solved with a highresolution shock-capturing WENO (weighted essentially non-oscillatory) scheme. The numerical simulations are used to obtain a clear picture of processes in the combustion chamber of CDWE, elucidate the underlying physical mechanisms, and investigate the influence of different parameters on this phenomenon.
arXiv (Cornell University), Jun 16, 2017
A generalized notion of a nonlocal tensor order parameter is introduced within the framework of t... more A generalized notion of a nonlocal tensor order parameter is introduced within the framework of the phenomenological approach. This parameter has the form of a traceless tensor correlation function or a tensor integral operator. Based on this form, the governing relations are written, which determine the steady states and phase transitions of the deformed liquid crystal. Linear relations for eigenfunctions of the introduced operator are derived. A principal drawback of currently available models of liquid crystals based on the local presentation of the tensor order parameter (equality of two Frank constants in the case of a quadratic form of the strain part of the free energy) is eliminated. Particular examples are considered, which demonstrate the model workability and the absence of contradictions in the model as well as its adequacy when describing small-scale structures.
Nucleation and Atmospheric Aerosols, 2023
ACTUAL PROBLEMS OF CONTINUUM MECHANICS: EXPERIMENT, THEORY, AND APPLICATIONS
Numerical simulation of the Rayleigh-Taylor instability in a plain layer of argon over a layer of... more Numerical simulation of the Rayleigh-Taylor instability in a plain layer of argon over a layer of helium in a field of gravitational force was performed using continuum and kinetic approaches. Continuum model is based on the Navier-Stokes equations for a gas mixture, kinetic approach is on the Direct Simulation Monte Carlo method. The onset of large-scale movement and mixing processes are investigated. Quantitative characteristics of the evolution of the Rayleigh-Taylor instability in a rarefied mode are obtained.
Combustion, Explosion, and Shock Waves, 2021
AIP Conference Proceedings, 2021
The effects of the surface undulation on the development of boundary layer instabilities are stud... more The effects of the surface undulation on the development of boundary layer instabilities are studied in the supersonic boundary layer. The direct numerical simulations are performed for the boundary layer on a flat plate at flow Mach number M = 6. The surface undulation is considered as the means of passive flow control of the laminar-turbulent transition. It has been found that a wavy portion of the surface located at some distance from the leading edge can significantly reduce the amplitude of fluctuations downstream. The effect of suppressing disturbances significantly increases with increasing both the number of waves on the surface (i.e., the length of the wavy portion), and their depth.
The results of numerical simulations of the propagation of the shock wave in a cylindrical shock ... more The results of numerical simulations of the propagation of the shock wave in a cylindrical shock tube of large length are presented. The results of the numerical computations agree well with the experimental data of Duff. The effects of viscous friction and heat conduction cause significant difference of the shock wave velocity from its inviscid theoretical value. The results of the computations at the considered flow parameters show that the shock wave and the contact surface, starting from a certain moment of time, propagate with equal speeds.
AIP Conference Proceedings, 2017
There are various methods for calculating rarefied gas flows, in particular, statistical methods ... more There are various methods for calculating rarefied gas flows, in particular, statistical methods and deterministic methods based on the finite-difference solutions of the Boltzmann nonlinear kinetic equation and on the solutions of model kinetic equations. There is no universal method; each has its disadvantages in terms of efficiency or accuracy. The choice of the method depends on the problem to be solved and on parameters of calculated flows. Qualitative theoretical arguments help to determine the range of parameters of effectively solved problems for each method; however, it is advisable to perform comparative tests of calculations of the classical problems performed by different methods and with different parameters to have quantitative confirmation of this reasoning. The paper provides the results of the calculations performed by the authors with the help of the Direct Simulation Monte Carlo method and finite-difference methods of solving the Boltzmann equation and model kinetic equations. Based on this comparison, conclusions are made on selecting a particular method for flow simulations in various ranges of flow parameters.
HIGH-ENERGY PROCESSES IN CONDENSED MATTER (HEPCM 2019): Proceedings of the XXVI Conference on High-Energy Processes in Condensed Matter, dedicated to the 150th anniversary of the birth of S.A. Chaplygin, 2019
Development of unstable two-dimensional and three-dimensional disturbances of various modes in th... more Development of unstable two-dimensional and three-dimensional disturbances of various modes in the boundary layer on the flat part of the model and their influence on the flow separation zone and the flow in the reattachment area on the compression ramp are studied with the direct numerical simulation. A supersonic flow with the flow Mach number M = 5.373 on a compression ramp with an angle of 5.5 degrees is simulated. The calculations are carried out using the CFD code HyCFS developed at the Laboratory of Computational Aerodynamics of the Institute of Theoretical and Applied Mechanics for solving the Navier-Stokes equations on hybrid-architecture computer clusters using graphical processing units. Based on the results of the numerical simulations data on the mean and nonstationary characteristics of the separated flow and surface characteristics in the vicinity of the boundary layer reattachment point have been obtained. The effect of developing large-scale turbulent structures in the transitional boundary layer on the fluctuations of the separation zone is studied, and the dynamics of critical parameters of the flow near the reattachment point is studied in detail. The calculation results show significant effect of the initial amplitudes of disturbances on the flow dynamics in the separation zone and the size of the zone. For sufficiently large amplitudes, laminar-turbulent transition occurs on the compression ramp.
AIP Conference Proceedings, 2017
Numerical simulation of detonation propagation in a plane channel with detailed chemical mechanis... more Numerical simulation of detonation propagation in a plane channel with detailed chemical mechanisms on supercomputers with GPUs
AIP Conference Proceedings, 2017
The results of three-dimensional numerical simulations of the interaction of the plane N-wave pro... more The results of three-dimensional numerical simulations of the interaction of the plane N-wave propagating at an angle to the free stream in the transverse direction with the sharp and blunted leading edges of the plate in a supersonic flow are presented. Interaction of the N-wave with a weak shock attached to the leading edge of the sharp plate causes corrugation of the shock wave surface that propagates downstream. A steady pressure perturbation is also formed that propagates inside the boundary layer in the transverse direction at an angle close to the Mach angle. This perturbation causes curving of the streamlines in the boundary layer and generation of a quasi-steady vorticity disturbance. In the case of the N-wave impinging on the leading edge of the blunted plate there is a large subsonic zone behind the bow shock where the pronounced oblique directivity of the disturbance transmitted through the shock is declined. Nevertheless, local disturbances of the flow parameters are observed in the boundary layer downstream of the region of the contact of the oblique shocks of the N-wave with the bow shock.
AIP Conference Proceedings, 2018
The effects of the surface roughness on mean flow distortion and generation of flow instabilities... more The effects of the surface roughness on mean flow distortion and generation of flow instabilities in a supersonic boundary layer on a blunted cone at flow Mach number 5.95 are studied with the direct numerical simulation. The considered cases include randomly distributed roughness, single roughness element, surface roughness combined with periodic blowing/suction disturbance, interaction of the group of roughness elements. Geometrical and dynamical conditions leading to the formation of intensive streamwise vortices downstream the roughness elements, growth of flow fluctuations in these vortices, and laminar-turbulent transition are discussed.
The numerical simulation of the unsteady effects in the interaction of an incident shock wave wit... more The numerical simulation of the unsteady effects in the interaction of an incident shock wave with the transitional flat-plate supersonic boundary layer has been performed. The Mach 2 supersonic boundary layer excited by unstable disturbances in the form of linear stability waves undergoes laminar-turbulent transition. An incident oblique shock wave impinges on the transitional boundary layer thus causing boundary layer separation. Large-scale turbulence structures evolving in the transitional boundary layer cause significant flow oscillations in the shock wave / boundary layer interaction region which manifests in fluctuations of the position and shape of the separation and reattachment lines, and also in staggering of the reflected shock wave.
AIP Conference Proceedings, 2008
Numerical simulations of shock wave propagation in microchannels and microtubes (viscous shock tu... more Numerical simulations of shock wave propagation in microchannels and microtubes (viscous shock tube problem) have been performed using three different approaches: the Navier-Stokes equations with the velocity slip and temperature jump boundary conditions, the statistical Direct Simulation Monte Carlo method for the Boltzmann equation, and the model kinetic Bhatnagar-Gross-Krook equation with the Shakhov equilibrium distribution function. Effects of flow rarefaction and dissipation are investigated and the results obtained with different approaches are compared. A parametric study of the problem for different Knudsen numbers and initial shock strengths is carried out using the Navier-Stokes computations.
AIP Conference Proceedings, 2011
TsAGI Science Journal, 2010
AIP Conference Proceedings, 2016
The effects of the distributed surface roughness on mean flow distortion and generation of flow i... more The effects of the distributed surface roughness on mean flow distortion and generation of flow instabilities in a supersonic boundary layer at Mach number 2 are studied with the direct numerical simulation. Roughness elements cause distortions of the mean flow field and flow unsteadiness in their wake. Farther downstream, growth of the fluctuations contained in the streamwise vortices and the interaction of the adjacent vortices lead to a breakup of the boundary layer manifesting the beginning of the laminar–turbulent transition.