E. Barrabés | Searcharxiv

arXiv2026

Analysis of travelling wave equations in sorption processes

This work presents a mathematical model of an adsorption column to study the evolution of contaminant concentration and adsorbed quantity along the longitudinal axis of the filter. The model is formulated as a system of partial differential equations (PDEs) and analysed using a travelling-wave approach, which reduces the system to a second-order ordinary differential equation depending on the inverse Péclet number, typically a small parameter. By neglecting this parameter, the model is simplified via a singular perturbation to a leading-order approximation, which can be interpreted as a slow-fast system. We rigorously justify this reduction by proving the persistence of the heteroclinic connection associated with the travelling wave. Using analytical continuation, we conclude that, at least for small values of the inverse Péclet number, the concentration profile transitions from a clean downstream state of the adsorbent matrix to fully upstream saturation. Numerical simulations are presented to validate the analytical results and to assess the accuracy of the reduced model. A sensitivity analysis demonstrates that the travelling-wave approximation remains remarkably robust for moderate values of the inverse Péclet number.

math-ph↗

arXiv2016

On central configurations of twisted crowns

We consider the planar central configurations of the Newtonian $κn$-body problem consisting in $κ$ groups of $n$-gons where all $n$ bodies in each group have the same mass, called $(κ, n)$-crown. We study the location and the number of central configurations when $κ=2$. For $n=3$ the number of central configurations varies depending on the mass ratio, whereas for $n\geq 4$ the number is at least three. We also prove that for $n\geq 3$ there always exist three disjoint regions where the configuration can be located. Finally, we study which $(κ, n)$-crowns are convex.

math.DS↗