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Description
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This dataset consists of the time-resolved three-dimensional velocity flow fields and the reconstructed point-clouds of the finite settling particles as described in the article titled: "Volumetric study of particle-wake interactions based on free falling finite particles" which is published in the Experiments in Fluids. The velocity vectors and the point-clouds were obtained via the Shake-The-Box technique and the Iterative Particle Reconstruction method, respectively. Four different particle geometries with a longest length scale of 12 mm and same volume (density ratio of 1.15) were investigated: sphere, circular cylinder, square cylinder and flat cuboid. The data set includes two different flow situation: 1) the particle was falling individually into the quiescent flow; 2) the particle was falling immediately after a group of 20 leading particles which generated a bulk wake. This work was funded by the European Union (see funding information): Views and opinions expressed are, however, those of the authors only and do not necessarily reflect those of the European Union, the Research Executive Agency, or the European Research Council Executive Agency. Neither the European Union nor the granting authority can be held responsible for them.
Abstract from the manuscript: Research on free falling particles has predominantly focused on wake dynamics and vortex shedding of individual particles in quiescent flow. However, when these particles fall collectively, the wakes of neighboring particles alter the flow fields. To investigate how the settling and wake dynamics of particles are affected by the wakes of other settling particles, we conducted volumetric experiments using the shake-the-box technique. Negatively buoyant 12 mm particles of four different geometries (sphere, flat cuboid, circular, and square cylinders) were first released individually into quiescent water. Subsequently, the particles were released individually into the bulk wakes of 20 monodisperse particles. Using four high-speed cameras and LEDs, we simultaneously captured both 3D particle and fluid motions in the terminal velocity regime. The imaging domain measured 90 mm × 90 mm × 40 mm. Our results show that all trailing particles settling through the bulk wakes gain additional downward momentum from the turbulent wakes, causing them to fall faster than in quiescent flow. However, when the induced velocity of the preceding wakes is subtracted, the relative settling velocity was found to be essentially the same as the particle falling in quiescent fluid. Upstream of the particle, the vortices in the bulk wake interact with the developing shear layer along the particle. The wake downstream of the trailing particle also appears more chaotic than that in quiescent flow.
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