arXiv subjects

Aoto Takahashi

Publications and source records attributed to Aoto Takahashi.

5 recordsLinked to original sources

arXiv2026

Local H theorem for Enskog and Enskog-Vlasov equations with a modified Enskog factor

The local H theorem is shown to hold for the Enskog equation with a modified Enskog factor proposed by the authors [Phys. Rev. E 111, 065108 (2025)]. This is a stronger statement than the global one in the same paper and has been obtained along the lines of Mareschal et al. [Phys. Rev. Lett. 52, 1169-1172 (1984)] for the modified (or revised) Enskog equation. Furthermore, it is shown that the local H theorem also holds for the corresponding Enskog-Vlasov equation.

math.AP↗

arXiv2026

Numerical analysis of the thermal relaxation of the dense gas between two parallel plates: the free energy monotonicity for the Enskog equation

The thermal relaxation problem between two parallel plates with the same temperature is investigated, aiming to study the behavior of the free energy of the dense gas described by the Enskog equation. Two types of Enskog equation have been used: one is the Enskog equation with the original Enskog factor, while the other is that with a modified Enskog factor proposed recently in Takata & Takahashi, Phys. Rev. E 111, 065108 (2025). The evaluated free energy is a natural extension of the thermodynamic free energy to the non-equilibrium state. It is observed that this free energy monotonically decreases in time for the modified factor version, while it is not necessarily the case for the original version. Differences are also observed in other quantities in their time evolutions, most typically in the density profile.

cond-mat.mes-hall↗

arXiv2025

Fluid-dynamic limit of the Enskog equation with the guaranteed H-theorem

The fluid-dynamic limit of the Enskog equation with a slight modification is discussed on the basis of the Chapman-Enskog method. This modified version of the Enskog equation has been shown recently by the present authors to ensure the H-theorem. In the present paper, it is shown that the modified version recovers the same fluid-dynamic description of the dense gas as the original Enskog equation, at least up to the level of the Navier-Stokes-Fourier set of equations inclusive. Since the original Enskog equation is known to recover the fluid-dynamical transport properties well, this result implies that the modified version of the Enskog equation provides consistent descriptions both thermodynamically and fluid-dynamically.

physics.flu-dyn↗

arXiv2025

Enskog and Enskog-Vlasov equations with a slightly modified correlation factor and their H theorem

A novel modification of the original Enskog equation is proposed. The modification is much simpler than that is made in the modified (or revised) Enskog equation proposed by van Beijeren \& Ernst in 1973 and does not require a consideration of many-body configuration. The proposed modification is general enough to be adapted to various equations of states for non-ideal gases. It is shown that the H-theorem can be established for the Enskog and the Enskog--Vlasov equation with the proposed modification.

cond-mat.stat-mech↗

arXiv2023

Note on the summational invariant and corresponding local Maxwellian for the Enskog equation

The summational invariant and the corresponding local Maxwellian that are compatible with the Enskog equation are discussed, with special interest in the presence of a boundary. The local Maxwellian corresponding to the summational invariant is restrictive compared to the case of the Boltzmann equation in the sense that a radial flow and time-dependent temperature are forbidden. However, a rigid body rotation with a constant angular velocity is admitted as in the case of the Boltzmann equation. The influence of the presence of a boundary is also discussed in simple situations.

math-ph↗