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Séminaire de A. Parola

The concept of buoyancy in complex fluids


The University of Insubria - Via Ravasi, 2 - 21100 Varese - Italy

The concept of buoyancy in complex fluids

The buoyancy concept proved extremely useful when applied to macroscopic objects immersed in a fluid, providing a simple expression for the total force acting on the body.
However, when dealing with nanometric particles in colloidal suspensions, correlations may play a leading role, enhancing the expected buoyancy by orders of magnitude and leading to novel, unexpected phenomena, like denser particles floating on top of a lighter fluid. In these circumstances, the buoyancy concept needs to be revisited.
We present a theoretical description of such a generalized buoyancy for bodies of different shapes and material density in sedimentation equilibrium,
also providing quantitative experimental confirmations of our predictions.

R.Piazza, S.Buzzaccaro, E.Secchi, A.Parola
Soft Matter 8, 7112 (2012)

A.Parola, S.Buzzaccaro, E.Secchi, R.Piazza
J. Chem. Phys. 138, 114907 (2013)