Laser speckle photography and particle image velocimetry: photographic film noise

1984 ◽  
Vol 23 (17) ◽  
pp. 2961 ◽  
Author(s):  
C. J. D. Pickering ◽  
N. A. Halliwell
Keyword(s):  
Particle Image Velocimetry ◽  
Particle Image ◽  
Laser Speckle ◽  
Photographic Film ◽  
Speckle Photography ◽  
Image Velocimetry

Key Issues in Measuring the Velocities of Nanoparticles in Nanofluids

2007 ◽  
Vol 364-366 ◽  
pp. 1111-1116 ◽  
Author(s):  
Ming Qian ◽  
Xiao Wu Ni ◽  
Jian Lu ◽  
Zhong Hua Shen
Keyword(s):  
Particle Image Velocimetry ◽  
Particle Image ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Laser Speckle ◽  
Experimental Setup ◽  
Particle Volume ◽  
Image Velocimetry ◽  
Speckle Patterns ◽  
Key Issues

Our recent work [1] theoretically revealed that speckles can be formed when nanofluids containing a modest volume fraction of nanoparticles are illuminated by a monochromatic laser beam. This paper focuses on the key issues, including the experimental setup, the particle volume fraction of the nanofluid, the flow velocity of the nanofluid and the diameter of the pipe, in measuring the velocities of nanoparticles in nanofluids with laser speckle velocimetry (LSV). First an experimental setup is established according to the optical characteristics of nanoparticle and the measuring principles of particle image velocimetry (PIV) and LSV. Then a conclusion is made from the experimental results that clear speckle patterns can be formed when the particle volume fraction is between 0.0005% and 0.002% is able to form. Finally, in order to make it applicable to utilize LSV to measure the velocities of nanoparticles in nanofluids that flow in pipe, nanofluids can not flow too fast and the diameter of the pipe should not be too small.

scholarly journals THERMOCAPILLARY MONITORING USING PARTICLE IMAGE VELOCIMETRY ASSOCIATED WITH DYNAMIC LASER SPECKLE

2020 ◽  
Vol 5 (1) ◽  
pp. 1-5
Author(s):  
Ellem Waleska Nascimento da Fonseca Contado ◽  
Roberto Alves Braga Júnior ◽  
Henrique Coelho Barbosa ◽  
Renan Oliveira Reis ◽  
Radhakrishna Prabhu
Keyword(s):  
Particle Image Velocimetry ◽  
Laser Beam ◽  
Velocity Distribution ◽  
Particle Image ◽  
Physical Phenomenon ◽  
Flow Analysis ◽  
Ccd Camera ◽  
Laser Speckle ◽  
Piv Technique ◽  
Image Velocimetry

Thermocapillarity is a physical phenomenon used in many industrial processes, mainly in the field of miniaturization. Thermocapillary forces are the base of thermocapillary pumping (TCP), in which a drop of liquid moves through a microchannel or flat surface after temperature gradient occurs. The objective of this work was to study the thermocapillary convection during pumping without inserting external particles, monitored by the Particle Image Velocimetry (PIV) technique. The experiment consisted of a Pasteur tube containing a yellow fluorescein solution (0.02, 0.04, 0.06, 0.08, and 0.1 Molar), illuminated by a laser beam of 545 nm, 40 mW. After 2 minutes of illumination, the thermocapillary movement occurred at a distance of 0.05 mm below the meniscus when using a laser beam of 545 nm, 3 mW. The images were captured by a charge-coupled device (CCD) camera and processed using the PIV technique. The results showed an internal conversion capacity between the intersystem crossing, vibrational, and relaxation phenomena, also demonstrating the potential for applying the proposed approach. The images presented velocity distribution caused by thermocapillarity. The PIV was a useful tool for convective flow analysis if connected to appropriate image processing and enhancement techniques. In conclusion, the research showed the images with velocity distribution caused by thermocapillarity.

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