Stability of the Steady-State Displacement of a Liquid Plug Driven by a Constant Pressure Difference along a Prewetted Capillary Tube

Abstract

In this work we study the stability of a liquid plug driven along a capillary tube by a constant pressure difference. The methodology is based on the analysis of the values of the steady-state film thickness as a function of the plug length and the Capillary number, when the pressure drop and the Laplace number are fixed; thus, we extend our previous work where the plug was forced to move at a constant speed [Campana; et al. Stability of the steady-state motion of a liquid plug in a capillary tube. Ind. Eng. Chem. Res. 2007, 46, 1803]. The stability charts, built for selected values of the Laplace number and a wide range of the dimensionless parameters, show the existence of a small stable region whose size increases as the Laplace number is augmented.