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M. Tokarchuk

Publications and source records attributed to M. Tokarchuk.

10 recordsLinked to original sources
arXiv2023

Generalized equations of hydrodynamics in fractional derivatives

We present a general approach for obtaining the generalized transport equations with fractional derivatives using the Liouville equation with fractional derivatives for a system of classical particles and the Zubarev non-equilibrium statistical operator (NSO) method within the Gibbs statistics. We obtain the non-Markov equations of hydrodynamics for the non-equilibrium average values of densities of particle number, momentum and energy of liquid in a spatially heterogeneous medium with a fractal structure. For isothermal processes ($\beta=1/k_{B}T =const$), the non-Markov Navier-Stokes equation in fractional derivatives is obtained. We consider models for the frequency dependence of memory function (viscosity), which lead to the Navier-Stokes equations in fractional derivatives in space and time.

cond-mat.stat-mech↗
arXiv2022

To the kinetic theory of dense gases and liquids. Calculation of quasi-equilibrium particle distribution functions by the method of collective variables

Based on a chain of BBGKI equations with a modified boundary condition that takes into account multiparticle correlations, kinetic equations in the approximate "pairs" collisions and in the polarization approximation, taking into account the interaction through the third particle, obtained. The specifics of the model representation of the pair potential of particle interaction through short-range and long-range parts were taken into account. In the case of the short-range potential in the form of the potential of solid spheres, the contribution of Enskog's revised theory to the complete integration of the collision of the kinetic equation is obtained. The collision integrals include paired quasi-equilibrium distribution functions that depend on the nonequilibrium mean values of the particle number density and the inverse temperature. The method of collective variables Yukhnovskii is applied for the calculation of pair quasi-equilibrium distribution function with an allocation of short-range and long-range parts in the potential of the interaction of particles. In this case, the system with short-range interaction is considered as a frame of reference.

cond-mat.stat-mech↗
arXiv2020

Generalized diffusion equation with nonlocality of space-time: analytical and numerical analysis

Based on the non-Markov diffusion equation taking into account the spatial fractality and modeling for the generalized coefficient of particle diffusion $D^{\alpha\alpha'}(\mathbf{r},\mathbf{r}';t,t')=W(t,t')\bar{D}^{\alpha\alpha'}(\mathbf{r},\mathbf{r}')$ using fractional calculus the generalized Cattaneo--Maxwell--type diffusion equation in fractional time and space derivatives has been obtained. In the case of a constant diffusion coefficient, analytical and numerical studies of the frequency spectrum for the Cattaneo--Maxwell diffusion equation in fractional time and space derivatives have been performed. Numerical calculations of the phase and group velocities with change of values of characteristic relaxation time, diffusion coefficient and indexes of temporal $\xi$ and spatial $\alpha$ fractality have been carried out.

cond-mat.stat-mech↗
arXiv2016

Generalized diffusion equation with fractional derivatives within Renyi statistics

By using the Zubarev nonequilibrium statistical operator method, and the Liouville equation with fractional derivatives, a generalized diffusion equation with fractional derivatives is obtained within the Renyi statistics. Averaging in generalized diffusion coefficient is performed with a power distribution with the Renyi parameter $q$.

cond-mat.stat-mech↗
arXiv2015

Effect of ion polarization on longitudinal excitations in ionic melts

A simplified model for a collective dynamics in ionic melts is proposed for the description of optic-like excitations. Within a polarization model of ionic melt the analytical expressions for optic and relaxation dipole modes are obtained. The considered model allows one to describe a softening of frequency and an increase of damping of optic modes caused by polarization processes in comparison with the rigid-ion model. The contributions related with ion polarization to time correlation functions are calculated.

cond-mat.soft↗
arXiv2013

Consistent description of kinetics and hydrodynamics of dusty plasma

A consistent statistical description of kinetics and hydrodynamics of dusty plasma is proposed based on the Zubarev nonequilibrium statistical operator method. For the case of partial dynamics the nonequilibrium statistical operator and the generalized transport equations for a consistent description of kinetics of dust particles and hydrodynamics of electrons, ions and neutral atoms are obtained. In the approximation of weakly nonequilibrium process a spectrum of collective excitations of dusty plasma is investigated in the hydrodynamic limit.

cond-mat.stat-mech↗
arXiv2013

Consistent description of kinetics and hydrodynamics of weakly nonequilibrium processes in simple liquids

The generalized transport equations for a consistent description of kinetic and hydrodynamic processes in dense gases and liquids are considered. The inner structure of the generalized transport kernels for these equations is established. It is shown how in this approach to obtain the transport equation of molecular hydrodynamics. For the model potential of interaction presented as a sum of the hard spheres potential and certain long-range potential a spectrum of collective modes in the system is investigated.

cond-mat.stat-mech↗
arXiv2012

Statistical Description of Hydrodynamic Processes in Ionic Melts with taking into account Polarization Effects

Statistical description of hydrodynamic processes for ionic melts is proposed with taking into account polarization effects caused by the deformation of external ionic shells. This description is carried out by means of the Zubarev nonequilibrium statistical operator method, appropriate for investigations of both strong and weak nonequilibrium processes. The nonequilibrium statistical operator and the generalized hydrodynamic equations that take into account polarization processes are received for ionic-polarization model of ionic molten salts when the nonequilibrium averaged values of densities of ions number, their momentum, dipole momentum and total energy are chosen for the reduced description parameters. A spectrum of collective excitations is investigated within the viscoelastic approximation for ion-polarization model of ionic melts.

cond-mat.stat-mech↗
arXiv2010

Nonequilibrium statistical operator method in the Renyi statistics

The generalization of the Zubarev nonequilibrium statistical operator method for the case of Renyi statistics is proposed when the relevant statistical operator (or distribution function) is obtained based on the principle of maximum for the Renyi entropy. The nonequilibrium statistical operator and corresponding generalized transport equations for the reduced-description parameters are obtained. A consistent description of kinetic and hydrodynamic processes in the system of interacting particles is considered as an example.

cond-mat.stat-mech↗