Seminar - Alejandro Álvarez Laguna - High-order moment models and numerical schemes for... скачать в хорошем качестве

Seminar - Alejandro Álvarez Laguna - High-order moment models and numerical schemes for...

High-order moment models and numerical schemes for partially-ionized plasmas Partially ionized plasmas frequently exhibit strong non-equilibrium distribution functions due to collisions with the background gas, as well as the presence of strong electric fields and spatial gradients. This non-equilibrium state often lies beyond the scope of classical fluid closures based on the Chapman-Enskog method (e.g., Fick’s, Ohm's or Fourier’s laws). Consequently, such systems typically require computationally intensive kinetic simulations. In this work, we investigate high-order moment models to capture the non-equilibrium state using a macroscopic set of equations. In this presentation, we will present a comparison of different high-order moment closures for ions and electrons in partially-ionized plasmas. In the presentation, we will describe the derivation of the collisional source terms in the moment equations from the Boltzmann operator as well as the consequences of the non-equilibrium in the transport. Similarly, we will discuss some of the numerical difficulties and methods in order to approximate the resulting stiff system of non-linear partially-differential system of equations. The numerical solution of the high-order moment models is benchmarked to kinetic simulations of an argon plasma at different pressure regimes, from nearly collisionless to collisionally-dominated.