Effect of magnetic field on hydrodynamic of a single bubble behavior in quiescent Newtonian fluid

In this paper, a single bubble free ascending in a vertical channel was studied experimentally. Five different Newtonian fluids were used where the surface tension force is dominant. The bubble trajectory was considered in water, glycerin 30 and 50 Vol% that is zigzag, however, linear behavior is observed while the weight concentration of the glycerin reaches to 80 and 100 percent. The bubble rise velocity and aspect ratio coefficient are calculated by image analysis via MATLAB software. The results are in a very good agreement with the literature for the bubble velocity. The effect of magnetic field (perpendicular to the bubble flow) on the hydrodynamic characteristics of the bubble for each of the working fluids has been scrutinized. Although the presence of the magnetic field does not affect the bubble trajectory type or change the flow pattern from zigzag to linear, but it reduces the flow domain where this descending trend decreases with the increase in viscosity. It should be also noted that the magnetic field causes the bubble rise velocity to increase while this enhancement increases with higher viscosity. The magnetic field effect on the bubble aspect ratio was also considered and it was found that as viscosity increases the aspect ratio change is decreases.