  Two generalisations of the blast-wave model to non-central nuclear collisions
are constructed, and elliptic flow as well as azimuthal dependence of
correlation radii are calculated. Particular attention is paid to how different
azimuthal dependences of transverse flow direction can cause qualitatively
different anisotropic fireballs to give same v_2 as a function of the
transverse momentum. The simultaneous dependence of v_2 and the oscillation of
correlation radii on both spatial and flow anisotropy is studied in great
detail.
