Plasma Physics Seminar

Developing Generally Applicable Data-Driven and Open Boundary Conditions for Magnetohydrodynamics Simulations
 

Speaker Name: Dylan Kee, GSFC

Abstract :
In constructing and analyzing three-dimensional, time-dependent magnetohydrodynamics simulations, it is common for the majority of the effort to be dedicated to the physics of the simulation interior. However, there are a variety of applications where a careful description of the boundary conditions is equally important. This is notably true when a substantial fraction of the plasma, energy, and magnetic field being modeled enter the simulation through one boundary and exit through a different one, as is for instance the case with simulations of the solar atmosphere. In such cases, representing the plasma state directly depends on the way these semi-permeable simulation boundaries are treated. Particularly, it is essential but non-trivial that these boundary conditions be specified in a way that is consistent with the underlying equations of magnetohydrodynamics (MHD), which govern the simulation as a whole.

In this seminar, I discuss so-called characteristics-based boundary conditions which naturally separate information entering the simulation from information leaving the simulation, thereby rendering the problem of appropriately specifying the numerical boundary condition more straightforward by ensuring that the boundary is neither under- nor over-specified at all locations and times. Specifically, I discuss a novel application of such boundary conditions to the problem of data-driving, where the simulation ingests a time-series of observationally inferred plasma properties on a 2D surface, e.g. the solar photosphere, as a direct boundary condition to the simulation. I also discuss the application of characteristics-based methods to general open boundaries where there are few if any a priori constraints.