Abstract
The MHD with embedded PIC (MHD-EPIC) model makes it feasible to
incorporate kinetic physics into a global simulation. Still, this
requires a large enough box-shaped PIC domain to accommodate the
movement and changes of the magnetic reconnection regions over time.
This wastes computational resources on simulating regions with the
expensive PIC model where MHD would be sufficient to describe the
physics. We have developed a new MHD with Adaptively Embedded PIC
(MHD-AEPIC) algorithm that couples the BATS-R-US MHD model with the new
FLexible Exascale Kinetic Simulator (FLEKS) PIC code. In the new coupled
model the PIC domains can move with the magnetic reconnection regions
and adapt to them with an arbitrary shape. In this work, we will first
introduce the algorithms for selecting the reconnection regions in the
MHD model that need to be resolved with the kinetic PIC model. Then we
will compare simulations obtained with MHD-EPIC using fixed PIC regions
versus MHD-AEPIC employing adaptive PIC regions to verify that the new
model generates reliable results. Finally, we will apply the MHD-AEPIC
model to a global magnetic storm simulation and demonstrate the improved
efficiency.