A study of bubble trajectory and drag co-efficient in water and non-Newtonian fluids

A new experimental set-up was used to analyze the characteristics of the bubbles rising in water and three different concentrations of xanthan gum solutions for higher Reynolds number. The bubble size, bubble rise velocity, and bubble trajectory were measured using a combination of non-intrusive-high speed photographic method and digital image processing. The results of bubble trajectory for various bubbles in water and different xanthan gum solutions are presented and discussed. In trajectory analysis, it is seen that the smaller bubbles show helical or zigzag motion and larger bubbles follow spiral motion for water. In xanthan gum solutions, small bubbles experience less horizontal motion than that in water. Larger bubbles produce more spiral motion with the increase in xanthan gum concentration. Drag coefficients for air bubbles at higher Reynolds number are reported . It is seen that the experimental drag coefficient increases with the increase in xanthan gum concentration corresponding to the same bubble volume.