Dresden 2017 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 62: Complex Fluids and Soft Matter II (joint DY/CPP)

DY 62.5: Talk

Friday, March 24, 2017, 10:45–11:00, HÜL 186

Structure and rheology of suspensions controlled by capillary forces in thin liquid films — •Andrea Scagliarini¹ and Jens Harting^1,2 — ¹Forschungszentrum Jülich GmbH, Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (IEK-11), Nürnberg, Germany — ²Department of Applied Physics, Eindhoven University of Technology, Eindhoven, The Netherlands

Commonly, the rheology of suspensions is primarily controlled by the volume fraction of solids, as it is the case, for instance, of colloidal gels. However, it has been recently shown that adding small amounts of a liquid, immiscible with the continuous phase of the suspension, affects strikingly the mechanical response of the system, even at low solid volume fraction, owing to the formation of particle aggregates and networks sustained by capillary forces. Such structures endow the material with elasto-plastic/gel-like properties which make these capillary suspensions particularly suitable for a number of applications. By means of lattice Boltzmann simulations I will address a number of open questions, concerning: i) the dependence of the network structure upon the particle shape and wettability, and, in turn, ii) the dependence of the rhelogical properties on such structure. In particular, I will show that by adding water to an oil-based suspension of strongly hydrophobic particles, the formation of a percolating cluster is observed. The percolation transition occurs at a critical value of the water volume fraction, for which we provide an explicit expression depending of the particle geometry, the solid volume fraction and the contact angle.