title: Dynamics of colloid accumulation under flow over porous obstacles.
abstract: The accumulation of colloidal particles to build dense structures from dilute suspensions may follow distinct routes. The mechanical, structural and geometrical properties of these structures depend on local hydrodynamics and colloidal interactions. Using model suspensions flowing into microfabricated porous obstacles, we investigate this interplay by tuning both the flow pattern and the ionic strength. We observe the formation of a large diversity of shapes, and demonstrate that growing structures in turn influence the local velocity pattern, favouring particle deposition either locally or over a wide front. We also show that these structures are labile, stabilised by the flow pushing on them, in low ionic strength conditions, or cohesive, in a gel-like state, at higher ionic strength. The interplay between aggregate cohesion and erosion thus selects preferential growth modes and therefore dictates the final shape of the structure.
authors.affiliation: IPR, UMR CNRS 6251, Campus Beaulieu, Université Rennes 1, 35042 Rennes, France. rdsv.matthieu@gmail.com.
authors.forename: Matthieu
authors.initials: M
authors.lastname: Robert de Saint Vincent
authors.affiliation: Centre de Biochimie Structurale, UMR 5048 CNRS/UM1, INSERM UMR 1054, 29 rue de Navacelles, 34090 Montpellier Cedex, France.
authors.forename: Manouk
authors.initials: M
authors.lastname: Abkarian
authors.affiliation: IPR, UMR CNRS 6251, Campus Beaulieu, Université Rennes 1, 35042 Rennes, France. rdsv.matthieu@gmail.com.
authors.forename: Hervé
authors.initials: H
authors.lastname: Tabuteau