  Numerical MHD simulations of 3D reconnection events in the solar corona have
improved enormously over the last few years, not only in resolution, but also
in their complexity, enabling more and more realistic modeling. Various ways to
obtain the initial magnetic field, different forms of solar atmospheric models
as well as diverse driving speeds and patterns have been employed. This study
considers differences between simulations with stratified and non-stratified
solar atmospheres, addresses the influence of the driving speed on the plasma
flow and energetics, and provides quantitative formulas for mapping electric
fields and dissipation levels obtained in numerical simulations to the
corresponding solar quantities. The simulations start out from a potential
magnetic field containing a null-point, obtained from a Solar and Heliospheric
Observatory (SOHO) magnetogram extrapolation approximately 8 hours before a
C-class flare was observed. The magnetic field is stressed with a boundary
motion pattern similar to - although simpler than - horizontal motions observed
by SOHO during the period preceding the flare. The general behavior is nearly
independent of the driving speed, and is also very similar in stratified and
non-stratified models, provided only that the boundary motions are slow enough.
The boundary motions cause a build-up of current sheets, mainly in the
fan-plane of the magnetic null-point, but do not result in a flare-like energy
release. The additional free energy required for the flare could have been
partly present in non-potential form in the initial state, with subsequent
additions from magnetic flux emergence or from components of the boundary
motion that were not represented by the idealized driving pattern.
