The interface configuration in two-phase stratified pipe flows

Exact analytical solution is obtained for the interface shape between two i mmiscible fluids and for the capillary pressure in the case of unidirection al axial laminar pipe flow. The solution is determined by three dimensionle ss parameters: the holdup, fluid/wall wettability angle and the Eotvos numb er, Eo = Delta rho g cos alpha R-2/sigma(12). The ranges of parameter value s, for which the model of flat interface (Eo-->infinity), or models of cons tant interfacial curvature can be applied, are explored. Finally, the impli cations to modeling of stratified flow characteristics and stability are di scussed. (C) 1999 Elsevier Science Ltd. All rights reserved.