  Within the framework of the Langevin equation, we study the energy loss of
heavy quark due to quasi-elastic multiple scatterings in a quark-gluon plasma
created by relativistic heavy-ion collisions. We investigate how the initial
configuration of the quark-gluon plasma as well as its properties affect the
final state spectra and elliptic flow of D meson and non-photonic electron. We
find that both the geometric anisotropy of the initial quark-gluon plasma and
the flow profiles of the hydrodynamic medium play important roles in the heavy
quark energy loss process and the development of elliptic flow. The relative
contribution from charm and bottom quarks is found to affect the transverse
momentum dependence of the quenching and flow patterns of heavy flavor decay
electron; such influence depends on the interaction strength between heavy
quark and the medium.
