In the framework of two-fluid approach, we consider different formulations of the stability of plane-parallel two-phase flows. New factors are taken into account, namely, non-uniform particle concentration and particle velocity slip in the main flow, Saffman lift force in the interphase momentum exchange and a finite particle volume fraction. The study is aimed at the analysis of the effect of these factors on the critical Reynolds number and the stability margins of two-phase flows in a plane channel and boundary layer.
