title: Geometric Mixing, Peristalsis, and the Geometric Phase of the Stomach.
abstract: Mixing fluid in a container at low Reynolds number--in an inertialess environment--is not a trivial task. Reciprocating motions merely lead to cycles of mixing and unmixing, so continuous rotation, as used in many technological applications, would appear to be necessary. However, there is another solution: movement of the walls in a cyclical fashion to introduce a geometric phase. We show using journal-bearing flow as a model that such geometric mixing is a general tool for using deformable boundaries that return to the same position to mix fluid at low Reynolds number. We then simulate a biological example: we show that mixing in the stomach functions because of the "belly phase," peristaltic movement of the walls in a cyclical fashion introduces a geometric phase that avoids unmixing.
authors.affiliation: Mediterranean Institute for Advanced Studies (CSIC-UIB), E-07190 Esporles, Spain; Área de Mecánica de Fluidos, Universidad Carlos III de Madrid, E-28911, Leganés, Spain.
authors.forename: Jorge
authors.initials: J
authors.lastname: Arrieta
authors.affiliation: Instituto Andaluz de Ciencias de la Tierra, CSIC-Universidad de Granada, Campus Fuentenueva, E-18071 Granada, Spain.
authors.forename: Julyan H E
authors.initials: JH
authors.lastname: Cartwright
authors.affiliation: Surface du Verre et Interfaces, UMR 125 CNRS/Saint-Gobain, 93303 Aubervilliers, France.
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Gouillart
authors.affiliation: École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Piro
authors.affiliation: Departament de Física, Universitat de les Illes Balears, E-07071 Palma de Mallorca, Spain.
authors.forename: Oreste
authors.initials: O
authors.lastname: Piro
authors.affiliation: Mediterranean Institute for Advanced Studies (CSIC-UIB), E-07190 Esporles, Spain.
authors.forename: Idan
authors.initials: I
authors.lastname: Tuval
mesh_terms: D000818:Animals; D003198:Computer Simulation; D005750:Gastric Juice / Q000502:physiology*; D006801:Humans; D008953:Models, Anatomic; D008954:Models, Biological; D017711:Nonlinear Dynamics; D010528:Peristalsis / Q000502:physiology*; D013270:Stomach / Q000502:physiology*