  The formation of the MFRs in the pre-flare stage, and how this leads to
coronal rain in a post-eruption magnetic loop is not fully understood. We
explore the formation, and eruption of MFRs, followed by the appearance of
coronal rain in the post-flare loops, to understand the magnetic and
thermodynamic properties of eruptive events and their multi-thermal aspects in
the solar atmosphere. We perform a resistive-magnetohydrodynamic (MHD)
simulation with the open-source code \texttt{MPI-AMRVAC} to explore the
evolution of sheared magnetic arcades that can lead to flux rope eruptions. The
system is in mechanical imbalance at the initial state, and evolves
self-consistently in a non-adiabatic atmosphere under the influence of
radiative losses, thermal conduction, and background heating. We use an
additional level of adaptive mesh refinement to achieve the smallest cell size
of $\approx 32.7$ km in each direction to reveal the fine structures in the
system. The system achieves a semi-equilibrium state after a short transient
evolution from its initial mechanically imbalanced condition. A series of
erupting MFRs is formed due to spontaneous magnetic reconnection, across
current sheets created underneath the erupting flux ropes. Gradual development
of thermal imbalance is noticed at a loop top in the post-eruption phase, which
leads to catastrophic cooling and formation of condensations. We obtain plasma
blobs which fall down along the magnetic loop in the form of coronal rain. The
dynamical and thermodynamic properties of these cool-condensations are in good
agreement with observations of post-flare coronal rain. The presented
simulation supports the development and eruption of multiple MFRs, and the
formation of coronal rain in post-flare loops, which is one of the key aspects
to reveal the coronal heating mystery in the solar atmosphere.
