Discussion thread: "14-moment maximum-entropy VDF: application to electrons in ExB fields"

[sbocce]

Hello, I'm Stefano Boccelli, and I'm a postdoc at the University of Ottawa, ON, Canada (supervisor: Prof. James McDonald).
At uOttawa, we develop maximum-entropy moment closures and apply them to various regimes (multiphase / rarefied flows, plasmas etc).

Maximum-entropy methods allow one to reproduce VDFs that are strongly out of equilibrium. In its most simple form, the max-ent method reproduces the Maxwellian VDF, but one can employ arbitrarily complex max-ent formulations, that introduce increasing levels of non-equilibrium.
In particular, in this work, we employ a "14-moment max-ent method". The result is a scheme that allows us to reproduce anisotropic & asymmetric VDFs, with non-Maxwellian kurtosis. The method also results in a set of closed-form balance laws that can be solved with a standard finite-volume method. The equations are:

• one mass equation
• 3 momentum eqs
• 6 eqs for the components of the pressure tensor (actually, for the momentum flux)
• 3 eqs for the heat flux components
• 1 eq for the 4th order moment (the "kurtosis" of the VDF)

In the slides, you can see some results from the max-ent method, compared to analytical VDFs for 0D electrons in ExB fields (no spatial gradients).

Feel free to write here any question / suggestion!
Stefano