Two-phase flows in pipes and capillary channels

This review is devoted to analysis of two-phase flow patterns in capillary channels. Studies are considered in which flow pattern maps are obtained of two-phase flow in channels of different cross sections with the transverse dimension ranging from 20 mu m to 255 mm. Data on flow patterns are systematized and given in tables. The impact made by capillary effects is analyzed compared to the influence of other factors under conditions of two-phase flow in channels. The classification of channels based on the degree of manifestation of capillarity is validated. Characteristic features of two-phase flow in channels of noncircular cross section are considered. It is demonstrated that thermocapillary effects may be significant under conditions of nonisothermal two-phase flow in microchannels and under conditions of weak effect of gravitation.