Seeding particles, particle image

Melling, A. (1997). Tracer particles and seeding for particle image velocimetry, Meas. Sci. and Technol. 8(12), 1406-1416. 

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... 

PLIF or Mie scatter on seeded particles). The pairs of scalar images were combined by making use of phase locked imaging. By changing the phase angle of the laser with respect to the vortex roll up cycle the time evolution of the mixing... 

In the gas-liquid two-phase flows illuminated by a laser sheet, for example, the intensity of light reflected from the gas-liquid interface (mostly the gas bubble s surface) not only saturate the CCD camera, but also overwhelm the intensity of light from the seeded tracer particles in its vicinity. Fluorescent particles are often used to realize the laser-induced fluorescence (LIF) technique together with PIV (e.g., Broder and Sommerfeld, 2002 Fujiwara et al., 2004a, b Kitagawa et al., 2005 Liu et al., 2005 Tokuhiro et al., 1998,1999), so that both images of gas-liquid interface (e.g., bubble s geometry) and velocity distribution in the liquid phase around the gas bubbles can be obtained. Issues on PIV measurement of gas-liquid two-phase flows will be further illustrated in the latter sections. 

Fig. 3 (A) Schematic of the LCG model. (B) TEM image of Si nanowires produced via LCG. (From Ref. (C) SEM image of GaP nanowires, single seed particle composed mostly of Au is shown in the inset. (D) HRTEM image of GaAso.6Po.4 nanowire with (111) growth axis. (E) CdSe nanowire with 18 nm diameter (wurtzite crystal structure is indicated in the inset). (From Ref. l) (View this art in color at www.dekker.com.)...

A very weU established non-intrusive technique to measure velocities in flows is the particle image velocimetiy (PIV). The adaptation of macroscopic PIV using a microscope was first described by Santiago et al. in 1998 [1] and successfully applied to microchannel flows. A schematic of a common setup is shown in Fig. 2 on the left side. The flow is seeded with small fluorescent tracer particles that should follow the fluid motion faithfully. Typically, lasers or LEDs are used to illuminate the particles twice with a short time separation At. The light emitted by the fluorescent particles at time t and t + At is recorded on individual frames of a CCD or (s) CMOS camera and the shift between... 

The PrV system consists of two Nd YAG lasers and a PIV camera to obtain two images of the flow with a known time separation. The particle image displacements are measured at many points in the image by the software to produce the flow field. The PIV system used for this study can be divided in the following subsystems seeding, laser system, syncbonizer and image capture camera. 

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