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- Resumen es exacto "The rise of bubbles in a thin-gap cell is a topic that has attracted the interest of researchers in recent years due to several practicalapplications, such as those involving photochemical reactions or aiming at microalgae harvesting, which is of great utility in the biofuel industry. This thesis consists of an experimental study of the rise of a single air bubble in a thin-gap cell (1 or 2.8 mm) saturated by water. In addition to the confinement due to the cell plates, lateral walls that allow to control the cell width W are included. In these conditions, inertial effects in the gap of the cell cannot be neglected. The influence of the lateral confinement on the motion of the bubble and of the fluid around it was characterized. Bubbles of different sizes and rise regimes were analyzed. The study focused on the regimes of bubbles with periodicpath and shape oscillations and of circular-capped and slugs bubbles. A regime that does not exist in the absence of lateral confinement, which consists of bubbles that have only shape oscillations, was also studied. In the regime of bubbles with path and shape oscillations it was found that, even though the bubble mean rise velocity is lower at stronger lateral confinement, the relative velocity between the bubble and the surrounding liquid does not depend on W for a bubble of a given size. The lateral confinement also modifies the shape of the bubbles, while the influence on the characteristic magnitudes of the oscillations is significantly lower. In the circular-capped regime, the shapes of the bubbles for the different lateral confinements and cell thicknesses were analyzed, and the influence of the thickness on the Froude number, that relates the bubble rise velocity with the cell width, was discussed. The three-dimensional velocity field surrounding the bubble and in its wake was measured using the Shake the-Box technique. Important three dimensional effects were observed both in the wakes of oscillating bubbles and in the slug regime. In addition, the emergence of vortices in the region close to the lateral walls was observed for the strongest lateral confinements. These vortices are not shed from the bubble surface but originate due to the interaction between the wake and the lateral walls. Finally, the movement and deformation of a bubble rising between lateral sinusoidal walls was characterized, for bubble sizes that are comparable to the distance between the walls. The influence of the distance between walls and of their geometry on the kinematics and shape of the bubble was studied."
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