An experimental study of the regimes of motion of spheres falling or ascending freely in a Newtonian fluid

Veldhuis, C.H.J. and Biesheuvel, A. (2007) An experimental study of the regimes of motion of spheres falling or ascending freely in a Newtonian fluid. International Journal of Multiphase Flow, 33 (10). pp. 1074-1087. ISSN 0301-9322

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Abstract:	This paper presents the results of an experimental investigation aimed at verifying some of the interesting conclusions of the numerical study by Jenny et al. concerning the instability and the transition of the motion of solid spheres falling or ascending freely in a Newtonian fluid. The phenomenon is governed by two dimensionsless parameters: the Galileo number G, and the ratio of the density of the spheres to that of the surrounding fluid ρs/ρ. Jenny et al. showed that the (G, ρs/ρ) parameter space may be divided into regions with distinct features of the trajectories followed eventually by the spheres after their release from rest. The characteristics of these ‘regimes of motion’ as described by Jenny et al., agree well with what was observed in our experiments. However, flow visualizations of the wakes of the spheres using a Schlieren optics technique raise doubts about another conclusion of Jenny et al., namely the absence of a bifid wake structure.
Item Type:	Article
Copyright:	© 2007 Elsevier
Faculty:	Engineering Technology (CTW)
Research Group:	Physics of Fluids (POF) Engineering Fluid Dynamics (EFD)
Link to this item:	http://purl.utwente.nl/publications/78624
Official URL:	http://dx.doi.org/10.1016/j.ijmultiphaseflow.2007.05.002
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