  We propose a new method to study transverse flow effects in relativistic
nuclear collisions by Fourier analysis of the azimuthal distribution on an
event-by-event basis in relatively narrow rapidity windows. The distributions
of Fourier coefficients provide direct information on the magnitude and type of
flow. Directivity and two dimensional sphericity tensor, widely used to analyze
flow, emerge naturally in our approach, since they correspond to the
distributions of the first and second harmonic coefficients, respectively. The
role of finite particle fluctuations and particle correlations is discussed.
