Particle image velocimetry analysis

The concept of the helical membrane module has been tested in a submerged membrane filtration mode with bubbling used for the membrane fouling control. Liu et al. [30] showed that the helical membrane with a twisted angle of 180° could achieve a 1.46-1.69 flux enhancement, compared to the membrane modules with 0° twisted angle, in the filtration of 500 mg/L kaolin suspension under a constant TMP of 2.8 and 3.2 kPa. The particle image velocimetry (PIV) analysis [31] showed that the tortured membrane surface of the helical membrane could generate rotational flow near the membrane surface and increase the wall shear rate. 

Recently the radial flow was measured experimentally using particle image velocimetry (PIV) analysis [54]. Interestingly, the velocity of a radial flow increased from zero at the center to its maximum at around 70 % of the radius of the droplet, which remained pinned during evaporation (Fig. 3.6) [54]. Interestingly, the intermediate radial position of maximum velocity within the droplet is not... 

In typical particle image velocimetry (PIV) analysis, the correlation of an image with itself is called an autocorrelation, and the correlation of an image with another image is called a crosscorrelation. The location of the correlation peak gives the average displacement of the particles,... 

To determine the displacement distributions on the surface of the limestone specimens, digital pictures of the specimen were taken to perform an image analysis technique, called Particle Image Velocimetry (PIV). 

A number of experimental measurement techniques are discussed, with a focus on noninvasive optical techniques such as particle image velocimetry and digital image analysis, as well as a number of academic numerical modeling tools such as discrete particle model and two-fluid model. Not only hydrodynamic aspects, such as the emergence of defluidized zones and solids circulation profile inversion, but also the effect on the bubble size distributions are discussed for wall-mounted membranes and horizontally immersed membranes. 

By confining the fluidized bed in one direction and using a translucent waU, visual access is restored so that the bed behavior can be studied fuUy and non-intrusively using optical techniques, such as particle image velocimetry (PIV) or digital image analysis (DIA), which are discussed in detail below. With these techniques, it is possible to obtain information on the instantaneous flow fields, but it remains difficult to translate the 2D results quantitatively to 3D. As a learning tool that allows to see and verify different aspects of the bed behavior (e.g., bubble size distribution, instantaneous particle fluxes) however, such techniques are unrivaled. The main focus of this chapter therefore lies on these optical techniques. 

De JongJF, Odu SO, van Buijtenen MS, Deen NG, van Sint Annaland M, Kuipers JAM Development and validation of a novel digital image analysis method for fluidized bed particle image velocimetry. Powder Technol 230 193—202, 2012a. 

Laverman JA, Roghair I, van Sint Annaland M, Kuipers JAM Investigation into the hydrodynamics of gas—solid fluidized beds using particle image velocimetry coupled with digital image analysis. Can J Chem Eng 86 523—535, 2008. 

Westerweel J Theoretical analysis of the measurement precision in particle image velocimetry, Exp Fluids 290 S3—S12, 2000. 

Spray properties are mostly determined with optical measurement techniques. For the analysis of the droplet diameter Shadowgraphic methods, laser diffraction or Phase Doppler Anemometry (PDA) have been used elsewhere [1, 2, 11, 18]. Droplet velocities can be measured with Shadowgraphy, Particle Image Velocimetry (PIV), or PDA [1, 6, 19]. The determination of the spray temperature is possible with Global Rainbow Thermometry (GRT), Planar Laser Induced Fluorescence (PLIF), and Differential Infrared Thermography (DIT) [20-22]. 

Image analysis Modern visualization techniques produce amazing images. Section 2.4 explains several important techniques to extract quantitative information from images including particle tracking, photoelastic force measurement, and particle imaging velocimetry. 

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