Direct Simulation of the Sedimentation of Elliptic Particles in Oldroyd-B Fluids

Loading...
Thumbnail Image
Penn collection
Departmental Papers (MEAM)
Degree type
Discipline
Subject
Engineering
Mechanical Engineering
Funder
Grant number
License
Copyright date
Distributor
Related resources
Author
Huang, P. Y.
Joseph, Daniel D.
Contributor
Abstract

Cross stream migration and stable orientations of elliptic particles falling in an Oldroyd-B fluid in a channel are studied. We show that the normal component of the extra stress on a rigid body vanishes; lateral forces and torques are determined by the pressure. Inertia turns the longside of the ellipse across the stream and elasticity turns it along the stream; tilted off-center falling is unstable. There are two critical numbers; elasticity and Mach numbers. When the elasticity number is smaller than critical the fluid is essentially Newtonian with broadside-on falling at the centerline of the channel. For larger elasticity numbers the settling turns the longside of the particle along the stream in the channel center for all velocities below a critical one, identified with a critical Mach number of order one. For larger Mach numbers the ellipse flips into broadside-on falling again. The critical numbers are functions of the channel blockage ratio, the particle aspect ratio and the retardation/relaxation time ratio of the fluid. Two ellipses falling nearby, attract, line-up and straighten-out in a long chain of ellipses with longside vertical, all in a row. Stable, off-center tilting is found for ellipses falling in shear thinning fluids and for cylinders with flat ends in which particles tend align their longest diameter with gravity.

Advisor
Date Range for Data Collection (Start Date)
Date Range for Data Collection (End Date)
Digital Object Identifier
Series name and number
Publication date
1997
Journal title
Volume number
Issue number
Publisher
Publisher DOI
Journal Issue
Comments
Suggested Citation: Huang, P.Y., Howard H. Hu and Daniel D. Joseph. (1997) Direct simulation of the sedimentation of elliptic particles in Oldroyd-B fluids. Journal of Fluid Mechanics. Vol. 362. p. 95-134. Copyright 1997 Cambridge University Press. http://dx.doi.org/10.1017/S0022112094000285
Recommended citation
Collection