arXiv subjects

Koudzo Togbévi Selom Sobah

Publications and source records attributed to Koudzo Togbévi Selom Sobah.

5 recordsLinked to original sources

arXiv2026

Global existence and uniqueness for the planar four-velocity Broadwell model with arbitrary $C^{1}$ bounded initial and boundary data in a rectangular domain

This paper establishes the global existence of classical solutions to the initial-boundary value problem for the planar four-velocity Broadwell model in a multidimensional setting. While uniqueness was already established in our previous work (which addressed existence under the assumption of sufficiently small, bounded, and $C^{1}$-regular initial and boundary data), the objective of the present study is to completely lift this size restriction. By extending the previously developed fixed-point framework, we prove that the methodology remains highly effective for arbitrary initial and boundary data. Within this generalized setting, both the solutions and their first-order partial derivatives are shown to be well-defined and to exist globally for all times.

math.AP↗

arXiv2026

Existence and uniqueness of classical solution to an initial-boundary value problem for the unsteady general planar Broadwell model with four velocities

We consider the unsteady problem for the general planar Broadwell model with four velocities in a rectangular spatial domain over a finite time interval. We impose a class of non-negative initial and Dirichlet boundary data that are bounded and continuous, along with their first-order partial derivatives. We then prove the existence and uniqueness of a non-negative continuous solution, bounded together with its first-order partial derivatives, to the initial-boundary value problem.

math.AP↗

arXiv2026

Global-in-time existence and uniqueness of classical solutions to the unsteady initial-boundary value problem for the four-velocity planar Broadwell model in a rectangular domain

Since the pioneering work of James E. Broadwell, discrete velocity models (DVMs) have played a fundamental role in approximating the Boltzmann equation and in the analysis of non-equilibrium gas dynamics. Despite their apparent simplicity, many fundamental analytical questions remain open, in particular the global existence and uniqueness of classical solutions, even for the widely studied four-velocity Broadwell model. In this paper, we establish the global-in-time existence and uniqueness of classical solutions to the nonstationary four-velocity Broadwell system in a rectangular domain. The analysis is carried out in a class of continuous functions possessing, except possibly on a finite number of planes, continuous first-order partial derivatives. Our approach is based on fixed point arguments combined with suitable a priori estimates that provide uniform bounds on the solution and its first-order partial derivatives. These bounds ensure that the solution remains controlled for all time and can be extended globally. We prove the existence of a unique bounded continuous solution whose first-order partial derivatives are also bounded. These results provide a rigorous well-posedness framework for this prototypical discrete velocity model and contribute to a deeper understanding of the analytical properties of discrete velocity models, which serve as systematic approximations of the Boltzmann equation in the study of non-equilibrium gas dynamics.

math.AP↗

arXiv2026

On the existence and uniqueness of classical solution for an initial-boundary value problem for a discrete Boltzmann system in two space dimensions

The initial-boundary value problem for the two-dimensional regular four-velocity discrete Boltzmann system is analyzed in a rectangle. The existence and uniqueness of a classical global positive solution, bounded with its first partial derivatives are proved for a range of bounded data by the use of fixed points tools. A bound for the solution and its partial derivatives is provided.

math.AP↗

arXiv2026

Global classical solutions for the general planar Broadwell model with arbitrary velocity orientation: a fixed-point framework

The present work extends a fixed-point framework previously developed for the standard planar four-velocity Broadwell model to the general four-velocity configuration with an arbitrary orientation of the discrete velocities. This provides a non-axis-aligned test of the framework and leads to a global-in-time existence and uniqueness result for classical solutions of the associated initial-boundary value problem in a rectangular domain. Under suitable assumptions on the initial and boundary data, we establish the existence and uniqueness of a global-in-time classical solution. The analysis identifies the geometric and analytic properties of the fixed-point approach that remain valid independently of the orientation of the discrete velocities. The results demonstrate the applicability of the framework to the general planar four-velocity Broadwell model beyond the standard axis-aligned configuration.

math.AP↗