  We study the dynamics of energy loss and flow of heavy quarks produced in
ultra-relativistic heavy-ion collisions within the framework of a Langevin
equation coupled to a (2+1)-dimensional viscous hydrodynamic model that
simulates the space-time evolution of the produced hot and dense QCD matter.
The classical Langevin approach is improved such that, apart from quasi-elastic
scatterings, radiative energy loss is incorporated by treating gluon radiation
as an additional force term. The hadronization of emitted heavy quarks is
simulated via a hybrid fragmentation plus recombination model. Our calculation
shows significant contribution from gluon radiation to heavy quark energy loss
at high energies, and we find the recombination mechanism is important for
heavy flavor meson production at intermediate energies. We present numerical
results for the nuclear modification and elliptic flow of D mesons, which are
consistent with measurements at both LHC and RHIC; predictions for B mesons are
also provided.
