title: Anti-inertial lift in foams: a signature of the elasticity of complex fluids.
abstract: To understand the mechanics of a complex fluid such as a foam we propose a model experiment (a bidimensional flow around an obstacle) for which an external sollicitation is applied, and a local response is measured, simultaneously. We observe that an asymmetric obstacle (cambered airfoil profile) experiences a downwards lift, opposite to the lift usually known (in a different context) in aerodynamics. Correlations of velocity, deformations, and pressure fields yield a clear explanation of this inverse lift, involving the elasticity of the foam. We argue that such an inverse lift is likely common to complex fluids with elasticity.
authors.affiliation: Laboratoire de Spectrométrie Physique, BP 87, Saint-Martin-d'Hères, France. h.dollet@tnw.utwente.nl
authors.forename: Benjamin
authors.initials: B
authors.lastname: Dollet
authors.forename: Miguel
authors.initials: M
authors.lastname: Aubouy
authors.forename: François
authors.initials: F
authors.lastname: Graner