  Collective anisotropic particle flow, a general phenomenon present in
relativistic heavy-ion collisions, can be separated from direct
particle-particle correlations of different physics origin by virtue of its
specific azimuthal pattern. We provide expressions for flow-induced
two-particle azimuthal correlations, if one of the particles is detected under
fixed directions with respect to the reaction plane. We consider an ideal case
when the reaction plane angle is exactly known, as well as present the general
expressions in case of finite event-plane resolution. We foresee applications
for the study of generic two-particle correlations at large transverse momentum
originating from jet fragmentation.
