  We consider general model with factorization between macroscopic flow and
matter decay distribution. We show universality of $p_t^2$ behavior of elliptic
flow at small $p_t$ for identified final particles in the symmetric nucleus
collision. At high $p_t$ we compare non-relativistic and relativistic models
for boosted decay distribution. In the relativistic models with distribution
having power-like tail we show existence of elliptic flow saturation. This
means that the elliptic flow value $v_2$ tend to constant at high $p_t$. We
discuss the importance of determination of elliptic flow orientation which can
help us to compare different models. For example, we introduce potential
expansion model which can reproduce azimuthal asymmetry but based on the
assumption that there are only cold strong forces and no thermalization. This
model show opposite sign of elliptic flow orientation in comparison with
thermal model. We also show that at small $p_t$ sign of elliptic flow can
change due to sign of second derivative of decay distribution. This fact tell
us that we must more carefully link elliptic flow sign and properties of the
model.
