  Experimental data from the Relativistic Heavy Ion Collider (RHIC) suggests
that the quark gluon plasma behaves almost like an ideal fluid. Due to its
short lifetime, many QGP properties can only be inferred indirectly through a
comparison of the final state measurements with transport model calculations.
Among the current phenomena of interest are the interdependencies between two
collective flow phenomena, elliptic and triangular flow. The former is mostly
related to the initial geometry and collective expansion of the system whereas
the latter is sensitive to the fluctuations of the initial state. For our
investigation we use a hybrid transport model based on the Ultra-relativistic
Quantum Molecular Dynamics (UrQMD) transport approach using an ideal
hydrodynamic expansion for the hot and dense stage. Using UrQMD initial
conditions for an Au-Au collision, particles resulting from a collision are
mapped into an energy density distribution that is evolved event-by-event with
a hydrodynamic calculation. By averaging these distributions over different
numbers of events, we have studied how the granularity/smoothness of the
distribution affects the initial eccentricity, the initial triangularity, and
the resulting flow components. The average elliptic flow in non central
collisions is not sensitive to the granularity, while triangular flow is. The
triangularity might thus provide a good measure of the amount of initial state
fluctuations that is necessary to reproduce the experimental data.

Nuclear Theory;High Energy Physics - Phenomenology;Nuclear Experiment