Taylor or slug flow regime in gas-liquid and liquid flow in small diameter channels has been extensively studied because of its hydrodynamic characteristics and consequent application in several micro-chemical processing,heat transfer and biomedical application.It is characterised by the regular and periodic flow a train of alternate long channel-size capsular bubbles/droplets and liquid slug on a slow moving thin film on the channel wall.As the flow is periodic,hydrodynamics of Taylor flow can be studied in a periodic unit cell consisting of a bubble and a liquid slug.When the gas flow rate is increased keeping liquid flow rate constant,the gas hold up or void fraction in a unit cell increases.Asadolahi et al.