Adapting a multi-grid method to a numerical simulation model of the interaction between Venus and the solar wind

Unlike Earth, Venus doesn’t have an intrinsic magnetic field shielding it from the solar wind. However, an induced
magnetic field is generated from the interaction of solar wind and the dense atmosphere of the planet. Recent
Venus flybys by the BepiColombo mission in October 2020 and August 2021, and by Parker Solar Probe and Solar
Orbiter, are unique opportunities to further study the interaction between Venus and the Sun.

Observational data are essential in the study of this interaction but they are limited by the mission’s trajectory,
offering a constrained view of the processes that take place. On the other hand, simulations offer a global view
of the interactions, allowing us to get results with physical significance that would not have been possible from
observational data only. LatHyS is a three-dimensional parallel multi-species model using the hybrid formalism,
that represents the electrons as a massless fluid conserving the neutrality of the plasma, and the ions by numerical
macroparticles with variable weights. Ions and electrons are coupled together using the Maxwell equations, and the
macroscopic plasma parameters determine the evolution of the magnetic field (Ledvina et al. 2008). It was initially
developed at LATMOS, Paris, France, for Mars (Modolo et al. 2005) and later parallelized (Modolo et al. 2016) for
performance and optimization purposes. It has the advantage of having a self consistently calculated ionosphere.
LatHyS was recently adapted to the simulations of the interaction between the solar wind and Venus at IRAP,
Toulouse, France (Aizawa et al. 2022).

The work conducted aims at adapting a multi-grid method, initially adapted to LatHyS by Leclercq et al. 2016
for the study of Mars and Ganymede, to the case of Venus. The multi-grid refinement allows a more efficient use
of computing resources and an improved accuracy of the simulation thanks to a spatial resolution equivalent to or
lower than the ionospheric plasma scale height.

First, the multi-grid method is presented. Then, simulations using the multi-grid method on the solar wind’s
interaction with Venus are conducted, and their results are compared to simulations made using LatHyS with a
single homogeneous grid.
Finally the outputs of the numerical simulations are compared to data on the magnetic field and charged particles
from recent flybys and from the Venus Express mission, that orbited the planet from 2006 to 2014.

 

References:

Aizawa et al. 2022. https://doi.org/10.1016/j.pss.2022.105499

Leclercq et al. 2016. http://dx.doi.org/10.1016/j.jcp.2016.01.005

Ledvina et al. 2008. http://dx.doi.org/10.1007/s11214-008-9384-6

Modolo et al. 2005. https://doi.org/10.5194/angeo-23-433-2005

Modolo et al. 2016. http://dx.doi.org/10.1002/2015JA022324