Date of Award


Document Type

Open Access

Degree Name

Bachelor of Science


Mechanical Engineering

First Advisor

Bradford Bruno




suface, tension, fluid, flow, field, propulsion


Bi-slugs are fluid entities involving two dissimilar fluids that move “on their own” due to differences in surface tension. At the micro-fluidic scale this sort of motion may be useful to efficiently transport small quantities of fluid from place to place. This study uses Micro-Particle Image Velocimetry (µ-PIV) techniques to investigate self propelling bi-slug flows. The bi-slugs examined are made of ethylene glycol and Xiameter PMX-200 Silicone Fluid (5cst and 10cst) and placed in a glass micro-channel of approximately 1mm diameter. The Reynolds number (Re) range considered (based on ethylene glycol in the slug) is 2.54 - 1.07 and the capillary number (Ca) range is 1.23x10-3 - 5.18x10-4. In particular, we are interested in the flow field in the region near the interfacial meniscus, and the shear forces along the micro-channel. Quantitative velocity field images and streamline images of the silicon fluid in motion are shown. To the best of the author’s knowledge these µ-PIV measurements are the first such measurements made in self propelling bi-slugs. In addition to the velocity field results, methods for creating self propelling bi-slugs, and issues related to the challenges of achieving adequate seeding of the ethylene glycol and silicone fluid with dyed micro-spheres will be presented.