Date of Award


Degree Type


Degree Name

Master of Engineering Science


Chemical and Biochemical Engineering


Dr. Argyrios Margaritis

Second Advisor

Dr. Maurice A. Bergougnou


Free motion of small air bubbles in the volume range of 1-1000 mm3 (microlitre) has been studied in a column with different concentrations of xanthan gum ranging from 520 to 2580 ppm (w∕w). Two high-speed cameras were used to capture the continuous movement of bubbles up to 2000 frames per second. The sizes as well as the rise velocities of bubbles were measured by means of an image analysis software connected to the cameras. A precise method has been developed to create bubbles with high accuracy and controlled specified volumes. One of the main objectives of this work was to investigate the presence of the often-reported discontinuity in the rise velocity versus volume of air bubbles in non-Newtonian fluids. No abrupt velocity change was observed in our studies for the bubble volume range from 1 to 100 microlitre, which has been reported to occur by some other researchers. A thorough rheological study on the working concentrations of xanthan gum has been performed to interpret the observations with the existing hypothesis in literature for velocity­ volume discontinuity. To be able to evaluate the results of the rise velocity for xanthan gum solutions in respect to the jump velocity, the same measurements were repeated

using two different concentrations of CMC, namely, 0.4% and 0.6% w/w as a second non-Newtonian fluid.



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