Liquid Permeation (and Sedimentation) of Dense Colloidal Hard-Sphere Packings

✍ Scribed by Albert P. Philipse; Chellappah Pathmamanoharan

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 706 KB
• Volume: 159
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.1993.1301

✦ Synopsis

Viscous flow in dense packings of well-characterized, uncharged, monodisperse colloidal silica spheres with various stabilizing coatings has been studied as a function of time, pressure, and sphere size. Permeabilities scaled with measured radii are constant, which is consistent with measured sphere volume fractions scattering over a small range around random close packing. The main result is that the relative permeability compares well with exact calculations of Zick and Homsy for fcc arrays of monodisperse spheres. This leads to the conclusion that the permeability of a dense packing depends primarily on the number of nearest neighlors, whereas strong hydrodynamic screening eliminates the inlluence of long-range order. The reported experiments complement earlier hard-sphere sedimentation results. The empirical Richardson-Zaki correlation ((1-\phi)^{4.9}) provides a reasonable estimate of sedimentation velocities at nearly all accessible volume fractions (\phi). (1993 Academic Press, Inc.