Particle image velocimetry principle

PIV has also been applied to gas-liquid systems (Reese and Fan, 1994 Lin et al, 1996) to study the flow structure in bubble columns. A specific complication here is caused by the presence of the gas bubbles. On the basis of a prior knowledge of the size distribution of the tracer particles and the gas bubbles it is possible to discriminate bubbles from particles and thus phase-specific postprocessing of the images can be undertaken whereby both the flow pattern of the bubbles and the liquid in principle can be obtained. Particle image velocimetry has also been applied (Chen and Fan, 1992) to study the flow structure in 3D gas-liquid-solid fluidized beds. 

Several techniques have been developed to measure the zeta potential, based on the principle of electrokinetics. In this entry, the conventional methods of measuring the zeta potential using the mechanisms of electrophoresis, streaming potential, and electroosmotic flow will be outlined first. Then, a novel method will be presented for simultaneously determining the zeta potentials of both the microchannel surfaces and the tracer particles by using the microscale particle image velocimetry (micro-PIV) technique. This method combines the theories of... 

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