  We introduce a transport approach at fixed shear viscosity to entropy ratio
$\etas$ to study the generation of collective flows in ultra-relativistic
heavy-ion collisions. Transport theory supplies a covariant approach valid also
at large $\etas$ and at intermediate transverse momentum $p_T$, where
deviations from equilibrium is no longer negligible. Such an approach shows
that at RHIC energies a temperature dependent $\etas$ enhances significantly
the $v_4/v_2^2$ respect to the case of constant $\etas$. Furthermore if NJL
chiral dynamics is self-consistently implemented we show that it does not
modify the relation between $v_2$ and $\etas$.
