A numerical and experimental study of the terminal velocity and shape of bubbles in viscous liquids

This paper presents an extensive comparison between numerical and experimental results for moderate deformed bubbles concerning their drag coefficient and deformation in the range (Re,We) = [1,100] x [0,5]. Experiments were made in tap water/glycerol mixtures and the numerical model is derived under the surfactant-free interface assumption. The experimental procedure and numerical model are presented in detail; the corresponding results are compared with other analytical, experimental and numerical studies. Finally, experimental and numerical data are compared in order to assess the ability of the numerical model to predict the bubble drag coefficient and aspect ratio in a practical situation. It is found that the Values predicted by the numerical model are generally in good agreement with the experimental results. (C) 1999 Elsevier Science Ltd. All rights reserved.