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HIGH-SENSITIVITY MULTIDIMENSIONAL PHOTOBLEACHING
VELOCIMETRY
by
Seungro Lee
------------------------------------------------------------------------
A Dissertation Presented to the
FACULTY OF THE GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(MECHANICAL ENGINEERING)
May 2008
Copyright 2008 Seungro Lee
Object Description
| Title | High-sensitivity multidimensional photobleaching velocimetry |
| Author | Lee, Seungro |
| Author email | seungrol@usc.edu |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Mechanical Engineering |
| School | Viterbi School of Engineering |
| Date defended/completed | 2008-03-26 |
| Date submitted | 2008 |
| Restricted until | Unrestricted |
| Date published | 2008-04-15 |
| Advisor (committee chair) | Ronney, Paul D. |
| Advisor (committee member) |
Pottebaum, Tait S. Shing, Katherine |
| Abstract | Many techniques have been developed for measuring convective flow velocities in liquids such as LDV, PIV, molecular tagging velocimetry, etc. A little-used method that is in principle much simpler than the aforementioned techniques is Photobleaching Velocimetry. A particularly attractive feature of this technique is that a single beam may be used for both tagging and probing, though for some applications separate beams may be desirable. A significant weakness of PV is that typically high laser power is needed to obtain sufficient photobleaching that significant contrast between low-velocity (highly-bleached) and high-velocity (less-bleached) regions can be obtained.; Recently, it was discovered that this disabling of fluorescence does not occur in the absenceof light and is a kinetically controlled process in the presence of light, and is reversible on a muchlonger time scale, thus the photobleaching solutions are re-usable. Furthermore, the laser intensityper unit volume of photobleached solution with the laser path is on the order of a few mW/cm3,thus no significant heating of the water occurs.; The circular pipe and Taylor-Couette flows were tested to test the viability of dithionitesensitized photobleaching as a velocimetry tool. As results of experiment, the relationship between fluorescence intensity and the known local velocity was nearly linear for a circular pipe flow. However, the observed relation was a linear, but not matched well due to wall curvature for the TC flow. To analyze this result, the numerical simulation was studied. According to this numerical analysis, the bleaching rate coefficient, fluoresced light coefficient and Gaussian beam width were found. The bleaching rate coefficient was matched very well with experiment result. So, if we assume the velocity with given coefficients or we know the intensity, the intensity will be estimated or the velocity will be calculated using this velocimetry.; In future studies, the utility of this photobleaching velocimetry will be tested in a turbulent pipe flow, the 4-roll mill and TC flow with a minimized curvature effect. If these studies further confirm the viability of the technique, it may emerge as a simple, easily interpreted alternative to LDV or PIV in many liquid-flow velocimetry applications. |
| Keyword | photobleaching; velocimetry |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Type | texts |
| Legacy record ID | usctheses-m1127 |
| Rights | Lee, Seungro |
| Repository name | Libraries, University of Southern California |
| Repository address | Los Angeles, California |
| Repository email | http://www.usc.edu/isd/libraries/services/ask_a_librarian/email/ |
| Filename | etd-LeeS-20080415 |
| Archival file | uscthesesreloadpub_Volume40/etd-LeeS-20080415.pdf |
Description
| Title | Page 1 |
| Full text | HIGH-SENSITIVITY MULTIDIMENSIONAL PHOTOBLEACHING VELOCIMETRY by Seungro Lee ------------------------------------------------------------------------ A Dissertation Presented to the FACULTY OF THE GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (MECHANICAL ENGINEERING) May 2008 Copyright 2008 Seungro Lee |
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