Particle imaging velocimetry

For most existing measuring methods, the actual motion of individual nano-particles in two-phase flow cannot be observed easily. Conventional particle image velocimetry (PIV) apparatus can measure the particles in micro scale... 

Kim, M. J., Beskok, A., and Kihm, K. D., "Electro-Osmosis-Driven Micro Channel Flows A Comparative Study of Microscopic Particle Image Velocimetry Measurements and Numerical Simulations, Exp. Fluids, Vol. 33, No. 1, 2002, pp. 170-180. 

On comparing the two flames, it is evident that the flow structure of the lean limit methane flame fundamentally differs from that of the limit propane one. In the flame coordinate system, the velocity field shows a stagnation zone in the central region of the methane flame bubble, just behind the flame front. In this region, the combustion products move upward with the flame and are not replaced by the new ones produced in the reaction zone. For methane, at the lean limit an accumulation of particle image velocimetry (PIV) seeding particles can be seen within the stagnation core, in... 

Hirasawa, T., Sung, C.J., Yang, Z., Joshi, A., Wang, H., and Law, C.K., Determination of laminar flame speeds of fuel blends using digital particle image velocimetry Ethylene, M-butane, and toluene flames, Proc. Combust. Inst., 29,1427, 2002. 

Figure 7.2.5 provides a visualization of a localized extinction event in a turbulent jet flame, using a temporal sequence of OH planar LIF measurements. The OH-LIF measurements, combined with particle image velocimetry (PIV) reveal that a distinct vortex within the turbulent flow distorts and consequently breaks the OH front. These localized extinction events occur intermittently as the strength of the coupling between the turbulent flow and the flame chemistry fluctuates. The characteristics of the turbulent flame can be significantly altered as the frequency of these events increases. 

Fajardo, C.M. and V. Sick, Flow field assessment in a fired spray-guided spark-ignition direct-injection engine based on UV particle image velocimetry with sub crank angle resolution. Proceedings of the Combustion Institute, 31(2) 3023-3031, 2007. 

There are many nonintrusive experimental tools available that can help scientists to develop a good picture of fluid dynamics and transport in chemical reactors. Laser Doppler velocimetry (LDV), particle image velocimetry (PIV) and sonar Doppler for velocity measurement, planar laser induced fluorescence (PLIF) for mixing studies, and high-speed cameras and tomography are very useful for multiphase studies. These experimental methods combined with computational fluid dynamics (CFDs) provide very good tools to understand what is happening in chemical reactors. 

Virdung, T. and Rasmuson, A. (2008) Solid-liquid flow at dilute concentrations in an axially stirred vessel investigated using particle image velocimetry. Chem. Eng. Commun., 195 (1), 18-34. 

Note that when solving the CFD transport equations, the mean velocity and turbulence state variables can be found independently from the mixture-fraction state variables. Likewise, when validating the CFD model predictions, the velocity and turbulence predictions can be measured in separate experiments (e.g., using particle-image velocimetry [PIV]) from the scalar field (e.g., using planar laser-induced fluorescence [PLIF]). 

Post, M. E., and L. P. Goss. 1993. Two-color particle-imaging velocimetry in vortex structures. 31st Aerospace Sciences Meeting Proceedings. AIAA Paper No. 93-0412. 

Other measurements of Hanratty s p have been made or inferred from various techniques, including a hot film probe just under the water surface (Brumley and Jirka, 1987), particle image velocimetry in a vertical laser sheet leading up to the water surface with a florescent dye to indicate water surface location accurately (Law and Khoo, 2002) and PIV on the water surface (McKenna and McGillis, 2004 Orlins and Gulliver, 2002). The measurements of Law and Khoo (2002) are especially interesting because the following relationship was developed from experiments on both a jet-stirred tank and a wind-wave channel ... 

M. Raffel, C.E. Wilier, J. Kompenhans, Particle Image Velocimetry A Practical... 

Feng-Chen Li and Koichi Hishida, Particle Image Velocimetry Techniques and Its Applications in Multiphase Systems... 

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