Starting from the collisional BGK model of the full Boltzmann equation, we develop an accurate and robust finite volume gas kinetic scheme on unstructured triangular mesh. The numerical approach is composed of two steps an initial reconstruction step and a gas evolution step. In the initial reconstruction step, the unstructured version of the LED (Local Extremum Diminishing) interpolation is ap...

We derive closure relations for a plasma fluid model, issued from the BGK equation for electrons in a strong magnetic-field. Our scaling of the BGK equation leads in the asymptotic limit ε → 0 towards the adiabatic electron regime, where ε embodies the scaled Larmor radius as well as a low Mach number. In this regime the electron density adjusts instantaneously to perturbations of the electric ...

Analytical solutions of the two dimensional triangular and square lattice Boltzmann BGK models have been obtained for the plain Poiseuille flow and the plain Couette flow. The analytical solutions are written in terms of the characteristic velocity of the flow, the single relaxation time τ and the lattice spacing. The analytic solutions are the exact representation of these two flows without an...

Numerical computations are presented of the BGK-like states that emerge beyond the saturation of the bump-on-tail instability in the Vlasov–Poisson system. The stability of these states towards subharmonic perturbations is explored in order to gauge whether the primary bump-on-tail instability always suffers a secondary instability that precipitates wave mergers and coarsening of the BGK patter...

Our purpose is to derive a model describing the evolution of particles at various scales following their kinetic energy. Fast particles will be described through a collisional kinetic equation of Boltzmann-BGK type. This equation will be coupled with a fluid model (Euler equations) that describes the evolution of slower particles. The main interest of this approach is to reduce the cost of nume...

Microflows occurring in MEMS are addressed by applying a continuum BEM code for quasi-static Stokes flow accounting for slip boundary condition. Working conditions typical of transition and rarefied flows are treated in a simplified manner by employing a viscosity corrected according to semi-analytical solutions for the linearized BGK model of Couette and Poiseuille flows. Numerical results are...