Single liquid slug motion in a horizontally oscillating circular tube is investigated---the liquid does not completely wet the tube wall and the slug velocity is not sufficiently large to deposit a macro-scale, Newtonian film. The focus of this study is to model the oscillatory contact line that constitutes the boundary condition for flows with interface---the moving contact line problem is singular in a traditional fluid dynamics sense. Additionally, mean motion of a slug through asymmetric forcing is sought. Corresponding experiments are conducted for a borosilicate glass tube and a treated water slug. For small tube motions where the contact lines are pinned or governed by a slip coefficient assumed small, spectral eigenvalue methods along with some lower-dimensional approximations are used to determine the natural frequencies of a liquid slug with curved end caps. The numerical results agree well with a spherical end cap approximation (0-D) for large aspect ratio slugs and with a membrane approximation (1-D) for small aspect ratios. The experimental observations for different aspect ratios agree well with the predictions, although the gravity, viscosity and/or slip are neglected in the analyses. Most previous oscillatory contact line models were based on observations of unidirectional creeping flows (Young & Davis-, Hocking). We pose a universal dynamic contact line model that accounts for unsteady effect based directly on experiments. This universal contact line model agrees well with the observations for a large range of frequencies for sinusoidal oscillations and does not have the restrictions as used by Miles (1990). The model is incorporated into a zero-dimensional simulation where viscosity and surface tension are treated in an approximate way. The simulation for the sinusoidal tube motions agrees well with the measurements. A net motion of the slug is achieved when the tube motion is asymmetric directionally, i.e., a periodic t2 function. The optimal pumping effect is studied experimentally as well as with a zero dimensional approach. The simulation predicts the region where the maximum pumping occurs, but the maximum pumping efficiency predicted is larger than the experiments. The mechanism has potential application for fluid handling in surface tension dominant flows.Ph.D.Applied SciencesMechanical engineeringOcean engineeringPlasma physicsPure SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/124019/2/3121893.pd
