The shape and drag coefficient for a single bubble rising in stagnant shear-thinning viscoelastic liquids

The motion of a single bubble rising in stagnant shear-thinning viscoelastic liquids was investigated using a high-speed camera. The recorded images were analyzed using MATLAB with a self-written code in order to obtain the bubble volume and velocity. Using the experimental observations, a simple shape map was proposed based on the Reynolds number and the Deborah number. The bubble velocity was also investigated, and the phenomenon of velocity jump was observed in the Polyacrylamide (PAA) solutions. Furthermore, an empirical correlation was proposed to predict the drag coefficient of bubbles rising in   stagnant shear-thinning viscoelastic   liquids. The predicted results of the correlation showed good conformity with the experimental values corresponding to the PAA solutions of different concentrations and 95 wt% glycerin solution.