Molecular tagging velocimetry

Maynes and Webb (2002) presented pressure drop, velocity and rms profile data for water flowing in a tube 0.705 mm in diameter, in the range of Re = 500-5,000. The velocity distribution in the cross-section of the tube was obtained using the molecular tagging velocimetry technique. The profiles for Re = 550,700,1,240, and 1,600 showed excellent agreement with laminar flow theory, as presented in Fig. 3.2. The profiles showed transitional behavior at Re > 2,100. In the range Re = 550-2,100 the Poiseuille number was Po = 64. 

Maynes D, Webb AR (2002) Velocity profile characterization in sub-diameter tubes using molecular tagging velocimetry. Exp Fluids 32 3-15... 

Hu H, Koochesfahani MM (2006) Molecular tagging velocimetry and thermometry and its application to the wake of a heated circular cylinder. Meas Sci Technol 6 1269... 

Koochesfahani MM, Nocera DG (2007) Molecular tagging velocimetry. In Foss J, Tropea C, Yarin A (eds) Handbook of experimental fluid dynamics. SpringCT, Berlin, Chapter 5.4... 

The term molecular tagging velocimetry first became popular in connection to phosphorescence tagging methods [8]. Originally employed in macroscale flow visualization studies [8], the so-called phosphorescent supramolecules have since been applied to visualization of relatively fast flows in microtubes. 

Gendrich CP, Koochesfahani MM, Nocera DG (1997) Molecular tagging velocimetry and other novel applications of a new phosphorescent supramolecule. Exp Fluids 23 361-372... 

Lempert WR, Magee K, Ronney P, Gee KR, Haugland RP (1995) Flow tagging velocimetry in incompressible flow using photoactivated nonintrusive tracking of molecular motion (PHANTOMM). Exp Fluids 18 249-257... 

Velocimetry is the measurement of fluid velocity. In the context of microfluidics and nanofluidics, velocimetry involves the determination of the velocity field in small-scale internal flows. Most commonly, velocimetry involves optical tracking of a fluid marker. In such cases, the terms flow visualization and velocimetry are used interchangeably. A variety of velocimetry methods have been developed for small-scale flows. Visualization-based methods can be divided into particle-based techniques such as microparticle image velocimetry and scalar-based techniques such as molecular tagging. Nonvisualization-based velocimetry methods have also been developed such as electrochemical velocimetry, where fluid velocity is determined via generation of a redox species. 

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