  We construct a theoretical framework to describe the evolution of heavy
flavors produced in relativistic heavy-ion collisions. The in-medium energy
loss of heavy quarks is described using our modified Langevin equation that
incorporates both quasi-elastic scatterings and the medium-induced gluon
radiation. The space-time profiles of the fireball is described by a
(2+1)-dimensional hydrodynamics simulation. A hybrid model of fragmentation and
coalescence is utilized for heavy quark hadronization, after which the produced
heavy mesons together with the soft hadrons produced from the bulk QGP are fed
into the hadron cascade UrQMD model to simulate the subsequent hadronic
interactions. We find that the medium-induced gluon radiation contributes
significantly to heavy quark energy loss at high $p_\mathrm{T}$; heavy-light
quark coalescence enhances heavy meson production at intermediate
$p_\mathrm{T}$; and scatterings inside the hadron gas further suppress the $D$
meson $R_\mathrm{AA}$ at large $p_\mathrm{T}$ and enhance its $v_2$. Our
calculations provide good descriptions of heavy meson suppression and elliptic
flow observed at both the LHC and RHIC.
