The centrality dependence of the charged multiplicity, transverse energy, and
elliptic flow coefficient is studied in a hydrodynamic model, using a variety
of different initializations which model the initial energy or entropy
production process as a hard or soft process, respectively. While the charged
multiplicity depends strongly on the chosen initialization, the p_t-integrated
elliptic flow for charged particles as a function of charged particle
multiplicity and the p_t-differential elliptic flow for charged particles in
minimum bias events turn out to be almost independent of the initial energy
density profile.Comment: 11 pages RevTex, including 10 postscript figures. Slightly modified
discussion of Figs. 5 and 6, updated references. This version to appear in
Nuclear Physics
