The velocity field around a Taylor bubble rising in a stagnant viscous fluid: numerical and experimental results

Particle image velocimetry (PIV) measurements have been made around a rising Taylor bubble. The bubble was produced by injecting air into a tube containing stagnant olive oil. The fluid properties and tube diameter yielded Eِtvِs=100, Morton=0.015, and Reynolds=27. Measurements were made in the region ahead of the bubble, in the falling film, and in the wake. The PIV system used pulsed Nd:YAG lasers and a digital cross-correlation camera. The measurements achieved a spatial resolution of 0.0079 tube diameters. Verification of the results was illustrated by a mass flow balance in the falling film. ow was also predicted using a volume-of-fluid based finite difference technique and the results compared to the PIV measurements. The comparison was very good over most of the flow and confirms the validity of the numerical model.