Free cooling and high-energy tails of granular gases with variable restitution coefficient

We prove the so-called generalized Haff's law yielding the optimal algebraic cooling rate of the temperature of a granular gas described by the homogeneous Boltzmann equation for inelastic interactions with non constant restitution coefficient. Our analysis is carried through a careful study of the infinite system of moments of the solution to the Boltzmann equation for granular gases and precise Lp estimates in the selfsimilar variables. In the process, we generalize several results on the Boltzmann collision operator obtained recently for homogeneous granular gases with constant restitution coefficient to a broader class of physical restitution coefficients that depend on the collision impact velocity. This generalization leads to the so-called L1-exponential tails theorem. for this model

Analysis of a chemotaxis system modeling ant foraging

In this paper we analyze a system of PDEs recently introduced in [P. Amorim, {\it Modeling ant foraging: a {chemotaxis} approach with pheromones and trail formation}], in order to describe the dynamics of ant foraging. The system is made of convection-diffusion-reaction equations, and the coupling is driven by chemotaxis mechanisms. We establish the well-posedness for the model, and investigate the regularity issue for a large class of integrable data. Our main focus is on the (physically relevant) two-dimensional case with boundary conditions, where we prove that the solutions remain bounded for all times. The proof involves a series of fine \emph{a priori} estimates in Lebesgue spaces.Comment: 39 page

Propagation of L1L^{1} and L∞L^{\infty} Maxwellian weighted bounds for derivatives of solutions to the homogeneous elastic Boltzmann Equation

We consider the $n$-dimensional space homogeneous Boltzmann equation for elastic collisions for variable hard potentials with Grad (angular) cutoff. We prove sharp moment inequalities, the propagation of $L^1$-Maxwellian weighted estimates, and consequently, the propagation $L^\infty$-Maxwellian weighted estimates to all derivatives of the initial value problem associated to the afore mentioned problem. More specifically, we extend to all derivatives of the initial value problem associated to this class of Boltzmann equations corresponding sharp moment (Povzner) inequalities and time propagation of $L^1$-Maxwellian weighted estimates as originally developed A.V. Bobylev in the case of hard spheres in 3 dimensions; an improved sharp moments inequalities to a larger class of angular cross sections and $L^1$-exponential bounds in the case of stationary states to Boltzmann equations for inelastic interaction problems with `heating' sources, by A.V. Bobylev, I.M. Gamba and V.Panferov, where high energy tail decay rates depend on the inelasticity coefficient and the the type of `heating' source; and more recently, extended to variable hard potentials with angular cutoff by I.M. Gamba, V. Panferov and C. Villani in the elastic case collision case and so $L^1$-Maxwellian weighted estimated were shown to propagate if initial states have such property. In addition, we also extend to all derivatives the propagation of $L^\infty$-Maxwellian weighted estimates to solutions of the initial value problem to the Boltzmann equations for elastic collisions for variable hard potentials with Grad (angular) cutoff.Comment: 24 page