  Hadron spectra and elliptic flow in high-energy heavy-ion collisions are
studied within a (3+1)D ideal hydrodynamic model with fluctuating initial
conditions given by the AMPT Monte Carlo model. Results from event-by-event
simulations are compared with experimental data at both RHIC and LHC energies.
Fluctuations in the initial energy density come from not only the number of
coherent soft interactions of overlapping nucleons but also incoherent
semi-hard parton scatterings in each binary nucleon collision. Mini-jets from
semi-hard parton scatterings are assumed to be locally thermalized through a
Gaussian smearing and give rise to non-vanishing initial local flow velocities.
Fluctuations in the initial flow velocities lead to harder transverse momentum
spectra of final hadrons due to non-vanishing initial radial flow velocities.
Initial fluctuations in rapidity distributions lead to expanding hot spots in
the longitudinal direction and are shown to cause a sizable reduction of final
hadron elliptic flow at large transverse momenta.
