  The heavy quark energy loss puzzle is explained by collective flow effects in
a dynamic medium. The dead cone and LPM effect are found to be changed
comparing to the static medium case. Instead of only one dead cone in the
static medium, the collective flow induces two dead cones from two different
kinds of processes. One is from the projectile emitting gluon process, the same
as that in the static medium. The other is from the gluon emission off the
exchanged gluon process, decreasing with increasing flow velocity $v_z$ along
jet direction, which lead to the increase of heavy quark energy loss. The
differences of the effective average energy loss among charm, bottom and light
quarks are very little from a full 3D ideal hydrodynamic simulation for 0-10$%$
central Au-Au collisions at RHIC energy. This would yield similar high $p_{T}$
suppressions between light and heavy quarks for central Au-Au collisions.
