The Turning Couples on an Elliptic Particle Settling in a Vertical Channel

P. Y. Huang, J. Feng and D. D. Joseph

*J. Fluid Mech.* 271, 1-16 (1994)

**Abstract** - We do a direct two-dimensional finite-element simulation
of the Navier-Stokes equations and compute the forces which turn an ellipse
settling in a vertical channel of viscous fluid in a regime in which the
ellipse oscillates under the action of vortex shedding. Turning this way
and that is induced by large and unequal values of negative pressure at the
rear separation points which are here identified with the two points on the
back face where the shear stress vanishes. The main restoring mechanism which
turns the broadside of the ellipse perpendicular to the fall is the high
pressure at the "stagnation point" on the front surface, as in potential
flow, which is here identified with the one point on the front face where
the shear stress vanishes.