KRM
Erratum to: Ghost effect by curvature in planar Couette flow [1]
Leif Arkeryd Raffaele Esposito Rossana Marra Anne Nouri
N/A
keywords: Couette flow. Boltzmann equation hydrodynamical limit ghost effect
KRM
A Milne problem from a Bose condensate with excitations
Leif Arkeryd Anne Nouri
This paper deals with a half-space linearized problem for the distribution function of the excitations in a Bose gas close to equilibrium. Existence and uniqueness of the solution, as well as its asymptotic properties are proven for a given energy flow. The problem differs from the ones for the classical Boltzmann and related equations, where the hydrodynamic mass flow along the half-line is constant. Here it is no more constant. Instead we use the energy flow which is constant, but no more hydrodynamic.
keywords: Milne problem. Low temperature kinetics Bose condensate two component model
KRM
Existence and uniqueness of the electric potential profile in the edge of tokamak plasmas when constrained by the plasma-wall boundary physics
Claudia Negulescu Anne Nouri Philippe Ghendrih Yanick Sarazin
The electric potential plays a key role in the confinement properties of tokamak plasmas, with the subsequent impact on the performances of fusion reactors. Understanding its structure in the peripheral plasma -- interacting with solid materials -- is of crucial importance, since it governs the boundary conditions for the burning core plasma. This paper aims at highlighting the dedicated impact of the plasma-wall boundary layer on this peripheral region. Especially, the physics of plasma-wall interactions leads to non-linear constraints along the magnetic field. In this framework, the existence and uniqueness of the electric potential profile are mathematically investigated. The working model is two-dimensional in space and time evolving.
keywords: Existence Plasma Energy estimate Fluid model Nonlinear boundary conditions Controlled fusion Uniqueness
KRM
Exponential stability of the solutions to the Boltzmann equation for the Benard problem
Leif Arkeryd Raffaele Esposito Rossana Marra Anne Nouri
We complete the result in [2] by showing the exponential decay of the perturbation of the laminar solution below the critical Rayleigh number and of the convective solutions above the critical Rayleigh number, in the kinetic framework.
keywords: Boltzmann equation hydrodynamical limit Benard problem.
KRM
Ghost effect by curvature in planar Couette flow
Leif Arkeryd Raffaele Esposito Rossana Marra Anne Nouri
We study a rarefied gas, described by the Boltzmann equation, between two coaxial rotating cylinders in the small Knudsen number regime. When the radius of the inner cylinder is suitably sent to infinity, the limiting evolution is expected to converge to a modified Couette flow which keeps memory of the vanishing curvature of the cylinders ( ghost effect [18]). In the $1$-d stationary case we prove the existence of a positive isolated $L_2$-solution to the Boltzmann equation and its convergence. This is obtained by means of a truncated bulk-boundary layer expansion which requires the study of a new Milne problem, and an estimate of the remainder based on a generalized spectral inequality.
keywords: Couette flow. Boltzmann equation Ghost effect Hydrodynamical limit
KRM
Derivation of a gyrokinetic model. Existence and uniqueness of specific stationary solution
Ghendrih Philippe Hauray Maxime Anne Nouri
A finite Larmor radius approximation is rigourously derived from the Vlasov equation, in the limit of large (and uniform) external magnetic field. Existence and uniqueness of a solution is proven in the stationary frame.
keywords: Plasmas gyrokinetic model steady state solutions.
KRM
Aggregated steady states of a kinetic model for chemotaxis
Anne Nouri Christian Schmeiser

A kinetic chemotaxis model with attractive interaction by quasistationary chemical signalling is considered. The special choice of the turning operator, with velocity jumps biased towards the chemical concentration gradient, permits closed ODE systems for moments of the distribution function of arbitrary order. The system for second order moments exhibits a critical mass phenomeneon. The main result is existence of an aggregated steady state for supercritical mass.

keywords: Chemotaxis stationary solutions aggregation moment systems critical mass

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