Near-Wall Convection in a Sedimenting Suspension of Fibers
2014 (English)In: AIChE Journal, ISSN 0001-1541, E-ISSN 1547-5905, Vol. 60, no 12, 4253-4265 p.Article in journal (Refereed) Published
The sedimentation of a fiber suspension near a vertical wall is investigated numerically. Initially, the near-wall convection is an upward backflow, which originates from the combined effects of the steric-depleted layer and a hydrodynamically depleted region near the wall. The formation of the hydrodynamically depleted region is elucidated by a convection-diffusion investigation, in which fibers are classified according to the different directions in which they drift. For fibers with sufficiently large aspect ratio, the initial near-wall backflow keeps growing. However, the backflow reverses to downward flow at later times if the aspect ratio is small. This is due to the fiber-wall interactions which rotate fibers to such angles that make fibers drift away from the wall, inducing a dense region and a correspondingly downward flow outside the initial backflow. Moreover, the steric-depleted boundary condition is of secondary importance in the generation and evolution of the near-wall convection.
Place, publisher, year, edition, pages
2014. Vol. 60, no 12, 4253-4265 p.
fibers, fluid mechanics, settling, sedimentation, multiphase flow
Fluid Mechanics and Acoustics
IdentifiersURN: urn:nbn:se:kth:diva-158802DOI: 10.1002/aic.14576ISI: 000345232900023ScopusID: 2-s2.0-84921843129OAI: oai:DiVA.org:kth-158802DiVA: diva2:785878
FunderSwedish Research Council
QC 201502042015-02-042015-01-122015-02-04Bibliographically approved