Thu January 21st 2010
16:00
ZH286
Seminar Drop impact of yield-stress fluids
Yoël Forterre

Details:

Drop impact of yield-stress materials occurs in different industrial applications (paint sprays, solid ink jet printing) and may serve as a laboratory model for investigating high-speed collision of solids (crater formation, ballistic impact, explosive welding). From a fluid mechanical point of view, this configuration provides an unusual test for the rheology of these complex fluids, for it involves large strains and shears on very short time scales.

In this talk, I will present an experimental study on the normal drop impact of yield-stress fluids on a flat rigid surface. Using different model fluids (polymer microgels, clay suspensions) and impacted surface (partially wettable, super-hydrophobic), a rich variety of impact regimes is found from irreversible viscoplastic coating to giant elastic spreading and recoil. We will see that classical Bingham-like rheologies are not sufficient to predict the observed phenomenology and that elasticity may be crucial to describe the hydrodynamics of these complex fluids. We will conclude by a discussion on the large drag reduction we observed on rough super-hydrophobic surfaces in some range of parameters.
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The 10th Complex Motion in Fluids 2021
Max Planck Gesellschaft
MCEC
Twente
Centre for Scientific Computing
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