Hydrodynamic characteristics of free rise of light solid particles and gasbubbles in non-Newtonian liquids

The main objective of this study was to determine the primary parameters af fecting the rise of gas bubbles and light solid particles in non-Newtonian (pseudoplastic) liquids. The results obtained for the rise of light solid p articles were used to explain the behavior of rising gas bubbles. These res ults were also compared to that of free-falling heavy particles. The main p arameters studied were the drag coefficient, trajectory of rise, and termin al velocity as a function of the shape and volume of gas bubbles and solid particles, and the rheological properties of the non-Newtonian (pseudoplast ic) liquid. It was determined that the most effective method for doing this was with a movable video camera unit. It was discovered that freely rising light solid particles have similar behavior to gas bubbles for a wide rang e of Reynolds numbers. This indicated that the hydrodynamics of freely risi ng light particles could be used to describe the behavior of gas bubbles. T he comparison of the behavior of light solid particles and gas bubbles allo wed us to determine the effect of the internal circulation of a gas bubble on the hydrodynamics of its rise. A new correlation was proposed to predict the drag coefficient and terminal velocity of gas bubbles in non-Newtonian (pseudoplastic) solutions. (C) 1999 Elsevier Science Ltd. All rights reser ved.