  ATLAS measurements of the azimuthal anisotropy in lead-lead collisions at
$\sqrt{s_{NN}}=2.76$ TeV are shown using a dataset of approximately 7
$\mu$b$^{-1}$ collected at the LHC in 2010. The measurements are performed for
charged particles with transverse momenta $0.5<p_T<20$ GeV and in the
pseudorapidity range $|\eta|<2.5$. The anisotropy is characterized by the
Fourier coefficients, $v_n$, of the charged-particle azimuthal angle
distribution for n = 2-4. The Fourier coefficients are evaluated using
multi-particle cumulants calculated with the generating function method.
Results on the transverse momentum, pseudorapidity and centrality dependence of
the $v_n$ coefficients are presented. The elliptic flow, $v_2$, is obtained
from the two-, four-, six- and eight-particle cumulants while higher-order
coefficients, $v_3$ and $v_4$, are determined with two- and four-particle
cumulants. Flow harmonics $v_n$ measured with four-particle cumulants are
significantly reduced compared to the measurement involving two-particle
cumulants. A comparison to $v_n$ measurements obtained using different analysis
methods and previously reported by the LHC experiments is also shown. Results
of measurements of flow fluctuations evaluated with multi-particle cumulants
are shown as a function of transverse momentum and the collision centrality.
Models of the initial spatial geometry and its fluctuations fail to describe
the flow fluctuations measurements.
