Authors

Samira Darvishi

Type

Text

Type

Thesis

Advisor

Thomas Cubaud | Thomas Cubaud. | Jon Longtin | David Hwang.

Date

2011-05-01

Keywords

Capillary threads, Folding instability, Laser microfabrication, Lubrication failure, Microfluidics, Viscous core-annular flow | Engineering

Department

Department of Mechanical Engineering

Language

en_US

Source

This work is sponsored by the Stony Brook University Graduate School in compliance with the requirements for completion of degree.

Identifier

http://hdl.handle.net/11401/71582

Publisher

The Graduate School, Stony Brook University: Stony Brook, NY.

Format

application/pdf

Abstract

Microfluidic devices were utilized to study the behavior of highly viscous liquids surrounded by less viscous ones. This study mainly focuses on the lubrication transition of viscous threads flowing in sheaths of less viscous fluids, i.e. | viscous core-annular flows. Miscible and immiscible fluid pairs with various viscosities, were tested in microchambers. A variety of flow patterns resulting from the viscous folding and capillary instabilities were observed and the relationships between flow morphologies and system parameters, including fluid viscosities, interfacial properties, flow rates of injection, and micro-cell geometry were examined. In addition, in order to fabricate microchannels more efficiently, a femtosecond laser was used to study the potential of ultrafast laser micromachining. Three disparate materials were tested to establish the ablation abilities of the laser. Each test piece was etched multiple times with different powers and the consequential geometrical parameters (height and width) of each etched trench were measured. The final result was shown on one master curve that works as a guideline for micromachining of tapered channels in transparent materials.

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