Most cited papers (RSCI)

221. Gorshkov A.V., Prosviryakov Y.Y.
     Layered Bénard–Marangoni convection during heat transfer according to the Newton’s law of cooling
     Computer Research and Modeling, 2016, v. 8, no. 6, pp. 927-940

     The paper considers mathematical modeling of layered Benard–Marangoni convection of a viscous incompressible fluid. The fluid moves in an infinitely extended layer. The Oberbeck–Boussinesq system describing layered Benard–Marangoni convection is overdetermined, since the vertical velocity is zero identically. We have a system of five equations to calculate two components of the velocity vector, temperature and pressure (three equations of impulse conservation, the incompressibility equation and the heat equation). A class of exact solutions is proposed for the solvability of the Oberbeck–Boussinesq system. The structure of the proposed solution is such that the incompressibility equation is satisfied identically. Thus, it is possible to eliminate the «extra» equation. The emphasis is on the study of heat exchange on the free layer boundary, which is considered rigid. In the description of thermocapillary convective motion, heat exchange is set according to the Newton’s law of cooling. The application of this heat distribution law leads to the third-kind initial-boundary value problem. It is shown that within the presented class of exact solutions to the Oberbeck–Boussinesq equations the overdetermined initial-boundary value problem is reduced to the Sturm–Liouville problem. Consequently, the hydrodynamic fields are expressed using trigonometric functions (the Fourier basis). A transcendental equation is obtained to determine the eigenvalues of the problem. This equation is solved numerically. The numerical analysis of the solutions of the system of evolutionary and gradient equations describing fluid flow is executed. Hydrodynamic fields are analyzed by a computational experiment. The existence of counterflows in the fluid layer is shown in the study of the boundary value problem. The existence of counterflows is equivalent to the presence of stagnation points in the fluid, and this testifies to the existence of a local extremum of the kinetic energy of the fluid. It has been established that each velocity component cannot have more than one zero value. Thus, the fluid flow is separated into two zones. The tangential stresses have different signs in these zones. Moreover, there is a fluid layer thickness at which the tangential stresses at the liquid layer equal to zero on the lower boundary. This physical effect is possible only for Newtonian fluids. The temperature and pressure fields have the same properties as velocities. All the nonstationary solutions approach the steady state in this case.

     Keywords: convection of Benard–Maragoni, analytical solutions, nonstationary problem.
     Views (last year): 10. Citations: 3 (RSCI).
222. Firsov A.A., Yarantsev D.A., Leonov S.B., Ivanov V.V.
     Numerical simulation of ethylene combustion in supersonic air flow
     Computer Research and Modeling, 2017, v. 9, no. 1, pp. 75-86

     In the present paper, we discuss the possibility of a simplified three-dimensional unsteady simulation of plasma-assisted combustion of gaseous fuel in a supersonic airflow. Simulation was performed by using FlowVision CFD software. Analysis of experimental geometry show that it has essentially 3D nature that conditioned by the discrete fuel injection into the flow as well as by the presence of the localized plasma filaments. Study proposes a variant of modeling geometry simplification based on symmetry of the aerodynamic duct and periodicity of the spatial inhomogeneities. Testing of modified FlowVision $k–\varepsilon$ turbulence model named «KEFV» was performed for supersonic flow conditions. Based on that detailed grid without wall functions was used the field of heat and near fuel injection area and surfaces remote from the key area was modeled with using of wall functions, that allowed us to significantly reduce the number of cells of the computational grid. Two steps significantly simplified a complex problem of the hydrocarbon fuel ignition by means of plasma generation. First, plasma formations were simulated by volumetric heat sources and secondly, fuel combustion is reduced to one brutto reaction. Calibration and parametric optimization of the fuel injection into the supersonic flow for IADT-50 JIHT RAS wind tunnel is made by means of simulation using FlowVision CFD software. Study demonstrates a rather good agreement between the experimental schlieren photo of the flow with fuel injection and synthetical one. Modeling of the flow with fuel injection and plasma generation for the facility T131 TSAGI combustion chamber geometry demonstrates a combustion mode for the set of experimental parameters. Study emphasizes the importance of the computational mesh adaptation and spatial resolution increasing for the volumetric heat sources that model electric discharge area. A reasonable qualitative agreement between experimental pressure distribution and modeling one confirms the possibility of limited application of such simplified modeling for the combustion in high-speed flow.

     Keywords: combustion in supersonic flow, numerical simulation, direct current discharge, plasma-assisted combustion.
     Views (last year): 8. Citations: 3 (RSCI).
223. Epifanov A.V., Tsybulin V.G.
     Regarding the dynamics of cosymmetric predator – prey systems
     Computer Research and Modeling, 2017, v. 9, no. 5, pp. 799-813

     To study nonlinear effects of biological species interactions numerical-analytical approach is being developed. The approach is based on the cosymmetry theory accounting for the phenomenon of the emergence of a continuous family of solutions to differential equations where each solution can be obtained from the appropriate initial state. In problems of mathematical ecology the onset of cosymmetry is usually connected with a number of relationships between the parameters of the system. When the relationships collapse families vanish, we get a finite number of isolated solutions instead of a continuum of solutions and transient process can be long-term, dynamics taking place in a neighborhood of a family that has vanished due to cosymmetry collapse.

     We consider a model for spatiotemporal competition of predators or prey with an account for directed migration, Holling type II functional response and nonlinear prey growth function permitting Alley effect. We found out the conditions on system parameters under which there is linear with respect to population densities cosymmetry. It is demonstated that cosymmetry exists for any resource function in case of heterogeneous habitat. Numerical experiment in MATLAB is applied to compute steady states and oscillatory regimes in case of spatial heterogeneity.

     The dynamics of three population interactions (two predators and a prey, two prey and a predator) are considered. The onset of families of stationary distributions and limit cycle branching out of equlibria of a family that lose stability are investigated in case of homogeneous habitat. The study of the system for two prey and a predator gave a wonderful result of species coexistence. We have found out parameter regions where three families of stable solutions can be realized: coexistence of two prey in absence of a predator, stationary and oscillatory distributions of three coexisting species. Cosymmetry collapse is analyzed and long-term transient dynamics leading to solutions with the exclusion of one of prey or extinction of a predator is established in the numerical experiment.

     Keywords: mathematical ecology, cosymmetry theory, competitor coexistence, predator – prey, Holling functional response, Alley effect.
     Views (last year): 12. Citations: 3 (RSCI).
224. Madera A.G.
     Modeling thermal feedback effect on thermal processes in electronic systems
     Computer Research and Modeling, 2018, v. 10, no. 4, pp. 483-494

     The article is devoted to the effect of thermal feedback, which occurs during the operation of integrated circuits and electronic systems with their use. Thermal feedback is due to the fact that the power consumed by the functioning of the microchip heats it and, due to the significant dependence of its electrical parameters on temperature, interactive interaction arises between its electrical and thermal processes. The effect of thermal feedback leads to a change in both electrical parameters and temperature levels in microcircuits. Positive thermal feedback is an undesirable phenomenon, because it causes the output of the electrical parameters of the microcircuits beyond the permissible values, the reduction in reliability and, in some cases, burn out. Negative thermal feedback is manifested in stabilizing the electrical and thermal regimes at lower temperature levels. Therefore, when designing microcircuits and electronic systems with their application, it is necessary to achieve the implementation of negative feedback. In this paper, we propose a method for modeling of thermal modes in electronic systems, taking into account the effect of thermal feedback. The method is based on introducing into the thermal model of the electronic system new model circuit elements that are nonlinearly dependent on temperature, the number of which is equal to the number of microcircuits in the electronic system. This approach makes it possible to apply matrix-topological equations of thermal processes to the thermal model with new circuit elements introduced into it and incorporate them into existing thermal design software packages. An example of modeling a thermal process in a real electronic system is presented, taking into account the effect of thermal feedback on the example of a microcircuit installed on a printed circuit board. It is shown that in order to adequately model the electrical and thermal processes of microcircuits and electronic systems, it is necessary to take into account the effects of thermal feedback in order to avoid design errors and create competitive electronic systems.

     Keywords: electronic system, microcircuit, thermal feedback, temperature, electrical parameters, thermal model, simulation.
     Views (last year): 22. Citations: 3 (RSCI).
225. Zhidkov E.P., Voloshina I.G., Polyakova R.V., Perepelkin E.E., Rossiyskaya N.S., Shavrina T.V., Yudin I.P.
     Computer modeling of magnet systems for physical setups
     Computer Research and Modeling, 2009, v. 1, no. 2, pp. 189-198

     This work gives results of numerical simulation of a superconducting magnetic focusing system. While modeling this system, special care was taken to achieve approximation accuracy over the condition u(∞)=0 by using Richardson method. The work presents the results of comparison of the magnetic field calculated distribution with measurements of the field performed on a modified magnet SP-40 of “MARUSYA” physical installation. This work also presents some results of numeric analysis of magnetic systems of “MARUSYA” physical installation with the purpose to study an opportunity of designing magnetic systems with predetermined characteristics of the magnetic field.

     Keywords: magnet systems, focusing system, Richardson method.
     Views (last year): 4. Citations: 2 (RSCI).
226. Rusanova Ya.M., Cherdyntseva M.I.
     Visualization of three-dimensional scenes. Technology for data storing and manipulating
     Computer Research and Modeling, 2009, v. 1, no. 2, pp. 119-127

     This article is devoted to some problems of declaring and storing information for objects' visualization. The storage structure and resources control technology can be applied for real-time visualization of three-dimensional scenes. Such instruments as Sample Framework from DirectX SDK and Direct3D Extension Library (D3DX) were used in the implementation.

     Keywords: 3D visualization, information storing.
     Views (last year): 2. Citations: 2 (RSCI).
227. Abaturova A.M., Kovalenko I.B., Riznichenko G.Yu., Rubin A.B.
     Investigation of complex formation of flavodoxin and photosystem 1 by means of direct multiparticle computer simulation
     Computer Research and Modeling, 2009, v. 1, no. 1, pp. 85-91

     Kinetics of complex formation between components of the photosynthetic electron transport chain — flavodoxin and membrane complex photosystem I has been studied using computer model based on methods of multiparticle simulation and Brownian dynamics. We simulated Brownian motion of several hundreds of flavodoxin molecules, taking into account electrostatic interactions and complex shape of the molecules. Our model could describe experimental nonmonotonic dependence of the association rate constant for flavodoxin and photosystem I. This lets us conclude that electrostatic interactions are sufficient to form such kind of nonmonotonic dependence.

     Keywords: flavodoxin, photosystem I, Brownian dynamics.
     Views (last year): 4. Citations: 2 (RSCI).
228. Koganov A.V.
     Occurence of contradictions in Zermelo–Fraenkel theory under extension of base language by recursion functions
     Computer Research and Modeling, 2009, v. 1, no. 4, pp. 367-380

     It is shown that the extension of base language in Zermelo–Fraenkel theory, which allows a relations on recursion function of natural argument, may lead in Set Theory to contradictive constructions on arithmetic level.

     Keywords: Zermelo–Fraenkel theory, recursion functions, set theory.
     Views (last year): 1. Citations: 2 (RSCI).
229. Zlenko D.V., Krasilnikov P.M.
     Permeability of lipid membranes. A molecular dynamic study
     Computer Research and Modeling, 2009, v. 1, no. 4, pp. 423-436

     A correct model of lipid molecule (distearoylphosphatidylcholine, DSPC) and lipid membrane in water was constructed. Model lipid membrane is stable and has a reliable energy distribution among degrees of freedom. Also after equilibration model system has spatial parameters very similar to those of real DSPC membrane in liquid-crystalline phase. This model was used for studying of lipid membrane permeability to oxygen and water molecules and sodium ion. We obtained the values for transmembrane mobility and diffusion coefficients profiles, which we used for effective permeability coefficients calculation. We found lipid membranes to have significant diffusional resistance to penetration not only by charged particles, such as ions, but also by nonpolar molecules, such as oxygen molecule. We propose theoretical approach for calculation of particle flow across a membrane, as well as methods for estimation of distribution coefficients between bilayer and water phase.

     Keywords: molecular modeling, lipid membranes, permeability, diffusion.
     Views (last year): 20. Citations: 2 (RSCI).
230. Fialko N.S.
     Mixed algorithm for modeling of charge transfer in DNA on long time intervals
     Computer Research and Modeling, 2010, v. 2, no. 1, pp. 63-72

     Charge transfer in DNA is simulated by a discrete Holstein model «quantum particle + classical site chain + interaction». Thermostat temperature is taken into account as stochastic force, which acts on classical sites (Langevin equation). Thus dynamics of charge migration along the chain is described by ODE system with stochastic right-hand side. To integrate the system numerically, algorithms of order 1 or 2 are usually applied. We developed «mixed» algorithm having 4th order of accuracy for fast «quantum» variables (note that in quantum subsystem the condition «sum of probabilities of charge being on site is time-constant» must be held), and 2nd order for slow classical variables, which are affecting by stochastic force. The algorithm allows us to calculate trajectories on longer time intervals as compared to standard algorithms. Model calculations of polaron disruption in homogeneous chain caused by temperature fluctuations are given as an example.

     Keywords: DNA, Holstein model, Langevin equation, integration algorithm for ODE with stochastic right-hand side.
     Views (last year): 2. Citations: 2 (RSCI).

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