Vector post-processing algorithm for phase discrimination of two-phase PIV

A Review on Multiphase Underwater Jets and Plumes: Droplets, Hydrodynamics, and Chemistry

“…Methods to measure the full‐field fluid motion of water in a multiphase bubble plume were just becoming mainstream when the DWH accident occurred (e.g., Simiano et al, 2006; Seol et al, 2007; Seol and Socolofsky, 2008; Bryant et al, 2009). These previous studies were effective at measuring the time‐average velocity field but, unless very high spatial and temporal resolution were used, could not resolve the turbulence down to the Kolomogorov scale.…”

“…The increasing complexity of integral models and growing capability of computational fluid dynamics (CFD) models in the early 2000s drove laboratory observations beyond observation of bulk properties and toward an understanding of velocity and turbulence field in bubble plumes. Seol and Socolofsky (2008) developed a method to apply particle image velocimetry (PIV) to bubble plumes and reported the mean velocity field for bubble plumes in Seol et al (2007). Seol et al (2009) also observed the unsteady behavior of bubble plumes in stratification and showed that bubble plume wandering in large reservoirs results from interaction of the bubble column with large, turbulent coherent structures in the entrained ambient fluid.…”

On image pre-processing for PIV of single- and two-phase flows over reflecting objects

“…While the normalization, stretching and background subtraction is sufficient to remove the stationary objects, the removal of non-stationary objects is accomplished by applying a mask to the moving objects. This procedure was specifically developed for the removal of bubbles, which appear as bright rings on the image and is similar to Seol and Socolofsky (2008). When other moving objects are present, the generation of the mask might require adaptations depending on the reflection pattern of the object (Fig.…”

“…Laser intensity can vary between images or image pairs due to differences in the two lasers (in case of a double-pulsed YAG laser), objects or bubbles can introduce strong reflections of light, and/or reflection from channel walls in confined flows introduce glow. Several approaches are available in literature to tackle these problems (Seol and Socolofsky 2008;Lindken and Merzkirch 2002;Honkanen and Nobach 2005;Westerweel 1993;Shavit et al 2007;Theunissen et al 2008). In the presence of static objects or in two-phase flow, fluorescent particles and a color filter are often used to avoid interference of the object edges in the correlation map.…”

“…In some cases, this will render the correlation rather difficult. Furthermore, fluorescent particles are about a factor ten more expensive than non-fluorescent particles, and calibration of the two cameras is more complicated (Seol and Socolofsky 2008).…”