  Flux ropes erupting from the vicinity of the black hole are thought to be a
potential model for the flares observed in Sgr\,A$^*$. In this study, we
examine the radiative properties of flux ropes that emerged from the vicinity
of the black hole. We have performed three-dimensional two-temperature General
Relativistic Magnetohydrodynamic (GRMHD) simulations of magnetized accretion
flows with alternating multiple magnetic loops, and General Relativistic
Radiation Transfer (GRRT) calculations. In GRMHD simulations, two different
sizes of initial magnetic loops are implemented. In the small loop case,
magnetic dissipation leads to a weaker excitement of magneto-rotational
instability inside the torus which generates a lower accretion rate compared to
the large loop case. However, it makes more generation of flux ropes due to
frequent reconnection by magnetic loops with different polarities. By
calculating the thermal synchrotron emission, we found that the variability of
light curves and emitting region are tightly related. At $230\,\rm GHz$ and
higher frequency, the emission from the flux ropes is relatively stronger
compared with the background, which is responsible for the filamentary
structure in the images. At lower frequencies, e.g. $43\,\rm GHz$, emission
comes from more extended regions, which have a less filamentary structure in
the image. Our study shows self-consistent electron temperature models are
essential for the calculation of thermal synchrotron radiation and the
morphology of the GRRT images. Flux ropes contribute considerable emission at
frequencies $\gtrsim 230\,\rm GHz$.
