arXiv subjects
Publications and source records attributed to Nils Caillerie.
We derive the hydrodynamic limit of a kinetic equation with a stochastic, short range perturbation of the velocity operator. Under some mixing hypotheses on the stochastic perturbation, we establish a diffusion-approximation result: the limit we obtain is a parabolic stochastic partial differential equation on the macroscopic parameter, the density here.
We study the dispersion of a particle whose motion dynamics can be described by a forced velocity jump process. To investigate large deviations results, we study the Chapman-Kolmogorov equation of this process in the hyperbolic scaling (t,x,v) -> (t/epsilon,x/epsilon,v) and then, perform a Hopf-Cole transform which gives us a kinetic equation on a potential. We prove the convergence of this potential to the solution of a Hamilton-Jacobi equation. The hamiltonian can have a C1 singularity, as was previously observed in this kind of studies. This is a preliminary work before studying spreading results for more realistic processes.
In this paper, we extend and complement previous works about propagation in kinetic reaction-transport equations. The model we study describes particles moving according to a velocity-jump process, and proliferating according to a reaction term of monostable type. We focus on the case of bounded velocities, having dimension higher than one. We extend previous results obtained by the first author with Calvez and Nadin in dimension one. We study the large time/large scale hyperbolic limit via an Hamilton-Jacobi framework together with the half-relaxed limits method. We deduce spreading results and the existence of travelling wave solutions. A crucial difference with the mono-dimensional case is the resolution of the spectral problem at the edge of the front, that yields potential singular velocity distributions. As a consequence, the minimal speed of propagation may not be determined by a first order condition.
We study a random process on R n moving in straight lines and changing randomly its velocity at random exponential times. We focus more precisely on the Kolmogorov equation in the hyperbolic scale (t, x, v) $\to$ t $ε$, x $ε$, v, with $ε$ \textgreater{} 0, before proceeding to a Hopf-Cole transform, which gives a kinetic equation on a potential. We show convergence as $ε$ $\to$ 0 of the potential towards the viscosity solution of a Hamilton-Jacobi equation $\partial$tÏ + H ($\nabla$xÏ) = 0 where the hamiltonian may lack C 1 regularity, which is quite unseen in this type of studies. R{é}sum{é}