Journal of Flow Visualization and Image Processing

ISSN for PRINT: 1065-3090

For Online Access

Best Paper Award Selection - Editorial Board Site

2001, Volume8

Issue 2-3

110 pages

Issue price - $280.00

J. S. Park
Department of Mechanical Engineering, Texas A&M University, College Station, TX 77843-3123, USA

H. J. Kim
Department of Mechanical Engineering, Texas A&M University, College Station, TX 77843-3123, USA

The development of a molecular tagging fluorescence velocimetry (MTFV) system is discussed, and measurement results are presented for a meso-scale flow field of a thermally driven capillary pore of 5 mm inner diameter that is tilted 5° from the horizon. The technique uses caged dextran conjugates of caged fluorescence dyes of less than 10 nm in size for tracers. The frequency-tripled ultra violet (UV) band (l = 355 nm) of a pulsed neodymium-yttrium-aluminum-garnef (Nd:YAG) laser uncages the molecules by photo-cleaving—that is, decomposition of a caging and a fluorescence chemical group. Then a continuous wave (CW) blue argon ion laser (l = 488 n) pumps the fluorescence of only those uncaged molecules whose emission band is centered at l = 518 nm, and a sequential recording of the fluorescence images are digitally created and analyzed for Lagrangian velocity field mapping. The use of the technique allows detailed measurements of the thermally driven three-dimensional flow inside a heated capillary pore. The measurements show that the meniscus surface flow is mainly driven by the thermocapillary stress field, resulting from the surface temperature gradient, while the bulk flow inside the pore is driven largely by the natural convection buoyancy.

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