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Abstract <p>Conditions are discussed for the self-consistent description of flows of large rod-shaped molecules inside the space of slit pores within the lattice gas model. The approach is based on the microscopic hydrodynamics ideas for the calculation of molecular flows. The surface potential of pore walls causes the layer-by-layer anisotropy of the distribution of mixture components along the normal to the surfaces. Particle migration and rotation processes are described within the transition state theory that takes into account the effect of adjacent molecules in dense phases on the activation barrier height. In the calculation of local distributions of mixture components in equilibrium states, lateral interactions are described in the approximation of isolated contacts. Three approximations of taking into account molecular interactions are considered, which differ in taking into account correlation effects: chaotic and mean field approximations without correlations and the quasi-chemical approximation (QCA) with regard to direct correlations. It is shown that only QCA corresponds to the self-consistent description of the equilibrium and reaction rates. Equations appear in the description of flows, which describe the translation and rotation of molecules and non-equilibrium corrections to the molecular pair distribution functions related to local hydrodynamic rates. They determine the local equilibrium conditions used in the calculation of local dissipative coefficients in any region of the system. The QCA application for the calculation of local internal pressures and viscosity coefficients ensure the agreement with the second law of thermodynamics. Possible generalizations of the theory are discussed.</p>

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Microscopic Simulation of Large Molecules in the Problems of Fluid Equilibrium and Flow in Dispersed Materials

  • 期刊论文

  • 发表日期：

    2026年6月25日

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  • Yu. K. Tovbin

摘要

Abstract

Conditions are discussed for the self-consistent description of flows of large rod-shaped molecules inside the space of slit pores within the lattice gas model. The approach is based on the microscopic hydrodynamics ideas for the calculation of molecular flows. The surface potential of pore walls causes the layer-by-layer anisotropy of the distribution of mixture components along the normal to the surfaces. Particle migration and rotation processes are described within the transition state theory that takes into account the effect of adjacent molecules in dense phases on the activation barrier height. In the calculation of local distributions of mixture components in equilibrium states, lateral interactions are described in the approximation of isolated contacts. Three approximations of taking into account molecular interactions are considered, which differ in taking into account correlation effects: chaotic and mean field approximations without correlations and the quasi-chemical approximation (QCA) with regard to direct correlations. It is shown that only QCA corresponds to the self-consistent description of the equilibrium and reaction rates. Equations appear in the description of flows, which describe the translation and rotation of molecules and non-equilibrium corrections to the molecular pair distribution functions related to local hydrodynamic rates. They determine the local equilibrium conditions used in the calculation of local dissipative coefficients in any region of the system. The QCA application for the calculation of local internal pressures and viscosity coefficients ensure the agreement with the second law of thermodynamics. Possible generalizations of the theory are discussed.