Thesis
Time periodic electroosmotic flow with non-uniformly charged surface
Washington State University
Master of Science (MS), Washington State University
2018
Handle:
https://hdl.handle.net/2376/101357
Abstract
Developing an effective micromixer is a challenging task due to very slow diffusion process. However, its demand has been exponentially increasing because mixing is a key mechanism for integrated microfluidic systems such as a lab-on-a-chip. In this paper, we have developed the analytical model for an electrokinetic mircomixer by time periodic electroosmosis. To facilitate mixing through micro-vortices, a non-uniform surface charge condition is considered. A generalized analytical solution is computed by using a stream function technique. The effectively thin electric double layer allows replacement of the electroosmotic body force with a slip boundary condition on the channel wall. The applicability of the analytical model has been shown by two different surface conditions: sinusoidal and step change in zeta potential along the channel surface. Depending on the zeta potential distribution at the wall, various types of flow patterns and vortices have been observed. The flow field is affected by channel height, and both spatial and temporal frequency changes. These factors correspond to either Stokes penetration depth or diffusion time scale, which determine the shape of flow structures. From our results, it is considered that sinusoidal change in zeta potential leads to more effective mixing rather than step change in zeta potential. This analytical model is expected to enhance micromixer design.
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Details
- Title
- Time periodic electroosmotic flow with non-uniformly charged surface
- Creators
- Hyunsung Kim
- Contributors
- Prashanta Dutta (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Mechanical and Materials Engineering, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525375601842
- Language
- English
- Resource Type
- Thesis