Sedimentation of cylindrical particles in a viscoelastic liquid: shape-tilting

✍ Scribed by Jing Wang; Run-yuan Bai; Craig Lewandowski; Giovanni P. Galdi; Daniel D. Joseph

• Publisher: Elsevier
• Year: 2004
• Tongue: English
• Weight: 356 KB
• Volume: 2
• Category: Article
• ISSN: 1672-2515
• DOI: 10.1016/s1672-2515(07)60014-1

✦ Synopsis

Aluminum and Teflon cylindrical particles with flat ends are dropped in aqueous Polyox solutions. The terminal equilibrium orientation of the particles is characterized by the tilt angle, α, formed by the major axis of the cylinder with the horizontal. It is observed that α is a function of the aspect ratio L=L/d, where L is the length and d is the diameter of the cylinder, and that it varies continuously from a certain angle, α 0 , to 90°, as L increases toward a value L 0 . For a given shape, both α 0 and L 0 depend on the density of the cylinder and the properties of the liquid used. For the particles we have considered the value of L 0 is of the order of 2. This "tilt-angle phenomenon" disappears as soon as the ends of the cylinder are round. Specifically, cylinders of the same density and with the same aspect ratio but with round ends, when dropped in the same polymeric solution will reach a final orientation with α=90°. Therefore, this tilt-angle phenomenon seems to be tightly related to the shape of the particle.