  One of the main dissipation processes acting on all scales in relativistic
jets is thought to be governed by magnetic reconnection. Such dissipation
processes have been studied in idealized environments, such as reconnection
layers, which evolve in merging islands and lead to the production of
plasmoids, ultimately resulting in efficient particle acceleration. In
accretion flows onto black holes, reconnection layers can be developed and
destroyed rapidly during the turbulent evolution of the flow. We present a
series of two-dimensional general-relativistic magnetohydrodynamic simulations
of tori accreting onto rotating black holes focusing our attention on the
formation and evolution of current sheets. Initially, the tori are endowed with
a poloidal magnetic field having a multi-loop structure along the radial
direction and with an alternating polarity. During reconnection processes,
plasmoids and plasmoid chains are developed leading to a flaring activity and
hence to a variable electromagnetic luminosity. We describe the methods
developed to track automatically the plasmoids that are generated and ejected
during the simulation, contrasting the behaviour of multi-loop initial data
with that encountered in typical simulations of accreting black holes having
initial dipolar field composed of one loop only. Finally, we discuss the
implications that our results have on the variability to be expected in
accreting supermassive black holes.
