TY - JOUR

T1 - Sedimentation of an elliptical object in a two-dimensional foam

AU - Davies, Ioan Tudur

AU - Cox, Simon John

N1 - I.T. Davies and S.J. Cox (2010) Sedimentation of an elliptical object in a two-dimensional foam. J. Non-Newt. Fl. Mech. 165:793-799.
Sponsorship: Financial support is gratefully acknowledged from EPSRC (EP/D071127/1).

PY - 2010/7

Y1 - 2010/7

N2 - The sedimentation of an elliptical object in a dry two-dimensional, monodisperse foam is simulated. The
calculations are quasi-static, allowing the identification and separation of the elastic, plastic and viscous
response of the foam to the motion. In addition to its weight, the forces on the ellipse are due to the network
of soap films and the pressures in the bubbles. These give rise to non-zero torque, lift and drag forces,
causing the motion of the ellipse to deviate from a vertical path. Highly-stretched films are formed in the
wake of the ellipse and asymmetry in the flow field, with bubbles moving from the front to the back of the
ellipse along only one side, causes it to rotate from a metastable state with its major axis perpendicular to
gravity into a stable orientation with its major axis parallel to the direction of gravity. When the orientation
is intermediate between these two limits, there is a significant lift force which causes the ellipse to move
laterally. A larger, more eccentric, ellipse rotates more quickly.

AB - The sedimentation of an elliptical object in a dry two-dimensional, monodisperse foam is simulated. The
calculations are quasi-static, allowing the identification and separation of the elastic, plastic and viscous
response of the foam to the motion. In addition to its weight, the forces on the ellipse are due to the network
of soap films and the pressures in the bubbles. These give rise to non-zero torque, lift and drag forces,
causing the motion of the ellipse to deviate from a vertical path. Highly-stretched films are formed in the
wake of the ellipse and asymmetry in the flow field, with bubbles moving from the front to the back of the
ellipse along only one side, causes it to rotate from a metastable state with its major axis perpendicular to
gravity into a stable orientation with its major axis parallel to the direction of gravity. When the orientation
is intermediate between these two limits, there is a significant lift force which causes the ellipse to move
laterally. A larger, more eccentric, ellipse rotates more quickly.

KW - Foam

KW - Ellipse

KW - Sedimentation

U2 - 10.1016/j.jnnfm.2010.04.005

DO - 10.1016/j.jnnfm.2010.04.005

M3 - Article

SN - 0377-0257

VL - 165

SP - 793

EP - 799

JO - Journal of Non-Newtonian Fluid Mechanics

JF - Journal of Non-Newtonian Fluid Mechanics

IS - 13-14

ER -