In this paper, we calculate the stopping power and temperature relaxation of dense plasmas on the basis of the Coulomb logarithm using the effective potentials. These potentials take into account long-range multi-particle screening effects and short-range quantum mechanical effects in two-temperature plasmas. Ion energy losses in the plasma for different values of temperature and plasma density are calculated. The obtained results are compared with the theoretical works of other authors and with the results of molecular dynamics simulations. KEYWORDSCoulomb logarithm, dense plasma, effective potentials, inertial confinement fusion, stopping power 1

In this paper, the relaxation properties of a fully ionized, hot, ideal plasma have been studied using the molecular dynamics method. As an example, the classical problem of equalization of the electron and ion temperatures for various mass ratios is considered, the relaxation times for temperatures is determined, and the influence of the number of particles and the type of boundary conditions on the simulation results is studied. The simulation results are compared with the available theoretical results. K E Y W O R D Sautocorrelation flow function, classical Coulomb system, Coulomb logarithm, mass ratio, mirror boundary conditions, molecular dynamics method, periodic boundary conditions, plasma, temperature relaxation 1

This paper considers the unstable stratified turbulent flow in an open channel. A mathematical model of unstable stratified turbulent flow is introduced, which allows to assess the mean and fluctuation characteristics of the turbulent flow. The numerical algorithm is developed for solving this problem. A numerical method is based on the projection method, which divides the problem into three stages. At the first stage, it is assumed that the transfer of momentum occurs only by convection and diffusion. Intermediate velocity field is solved by fractional steps method. At the second stage, three-dimensional Poisson equation is solved by the Fourier method in combination with tridiagonal matrix method (Thomas algorithm). Finally, at the third stage, it is expected that the transfer is only due to the pressure gradient. The simulation results are in satisfactory agreement with the experimental data.

Purpose This paper aims to propose a mathematical model and numerical modeling to study the behavior of low conductive incompressible multicomponent hydrocarbon mixture in a channel under the influence of electron irradiation. In addition, it also aims to present additional mechanisms to study the radiation transfer and the separation of the mixture’s components. Design/methodology/approach The three-dimensional non-stationary Navier–Stokes equation is the basis for this model. The Adams–Bashforth scheme is used to solve the convective terms of the equation of motion using a fourth-order accuracy five-point elimination method, and the viscous terms are computed with the Crank–Nicolson method. The Poisson equation is solved with the matrix sweep method and the concentration and electron irradiation equations are solved with the Crank–Nicolson method too. Findings It shows high computational efficiency and good estimation quality. On the basis of numerical results of mathematical model, the effect of the separation of mixture to fractions with various physical characteristics was obtained. The obtained results contribute to the improvement of technologies for obtaining high-quality oil products through oil separation into light and heavy fractions. Mathematical model is approbated based on test problem, and has good agreement with the experimental data. Originality/value The constructed mathematical model makes developing a methodology for conducting experimental studies of this phenomenon possible.

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