A study on the flow of moderate and high viscosity ratio emulsion through a cylindrical tube

This work deals with asymptotic and numerical solutions for emulsion flowing driven by a pressure gradient. The average macroscopic description of a homogeneous continuous emulsion of high viscosity drops is modeled. A parameter involving the product of the squares of the capillary number and the aspect ratio is the key parameter for developing a new asymptotic solution. Explicit expressions of the velocity profile, the flow rate correction due to the drops stress contribution, drop deformation, and the relative viscosity of the emulsion are shown as function of the capillary number ranging from 0 to 10 and emulsion viscosity ratio ranging from 2 to 20. The theoretical predictions by asymptotic theories developed in this work are compared with those computed results by boundary integral method (BIM) for different viscosity ratios of a dilute emulsion undergoing both pressure-driven flow and linear shear flow. Some discrepancies observed for moderate viscosity ratio are identified and discussed. The present study for emulsion with moderate and high viscosity ratio and arbitrary capillary number are still few explored in the current literature.