  Magnetohydrodynamics of the solar corona is simulated numerically. The
simulation is initialized with an extrapolated non-force-free magnetic field
using the vector magnetogram of the active region (AR) NOAA 12192 obtained on
the solar photosphere. Particularly, we focus on the magnetic reconnections
occurring close to a magnetic null-point that resulted in appearance of
circular chromospheric flare ribbons on October 24, 2014 around 21:21 UT, after
peak of an X3.1 flare. The extrapolated field lines show the presence of the
three-dimensional (3D) null near one of the polarity inversion lines---where
the flare was observed. In the subsequent numerical simulation, we find
magnetic reconnections occurring near the null point, where the magnetic field
lines from the fan-plane of the 3D null form a X-type configuration with
underlying arcade field lines. The footpoints of the dome-shaped field lines,
inherent to the 3D null, show high gradients of the squashing factor. We find
slipping reconnections at these quasi-separatrix layers, which are co-located
with the post-flare circular brightening observed at the chromospheric heights.
This demonstrates the viability of the initial non-force-free field along with
the dynamics it initiates. Moreover, the initial field and its simulated
evolution is found to be devoid of any flux rope, which is in congruence with
the confined nature of the flare.
