  Azimuthal anisotropy is studied by taking into account the ridges created by
semi-hard scattering, which is sensitive to the initial spatial configuration
in non-central heavy-ion collisions. No rapid thermalization is required.
Although hydrodynamics is not used in this study, the validity of
hydrodynamical expansion is not excluded at later time after equilibration is
achieved. Phenomenological properties of the bulk and ridge behaviors are used
as inputs to determine the elliptic flow of pion and proton at low p_T. At
intermediate p_T the recombination of shower partons with thermal partons
becomes more important. The phi dependence arises from the variation of the
in-medium path length of the hard parton that generates the shower. The p_T
dependence of v_2 is therefore very different at intermediate p_T compared to
that at low p_T. Quark number scaling of v_2 is shown to be only approximately
valid at low p_T, but is broken at intermediate p_T, even though recombination
is the mechanism of hadronization in all p_T regions considered.
