Volume 80, Number 3, November 2007
Article Number 34001
Number of page(s) 6
Section Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics, and Fluid Dynamics
Published online 24 September 2007
EPL, 80 (2007) 34001
DOI: 10.1209/0295-5075/80/34001

Rheology and dynamics of a deformable object in a microfluidic configuration: A numerical study

P. Peyla

Laboratoire de Spectrométrie Physique, Université Joseph Fourier - Grenoble 1, BP87, F-38402 Saint Martin d'Hères, France

received 24 January 2007; accepted in final form 3 September 2007; published November 2007
published online 24 September 2007

A dilute suspension is studied in a confined geometry with a 3D numerical simulation. The suspended element is a non-Brownian elastic dumbbell. The suspension is confined between two walls in a shear flow. The dynamics of the dumbbell as well as the associated rheology are presented. Despite its simplicity, the system exhibits generic microscopic behaviours of real deformable objects such as vesicles, biological cells or capsules like tumbling or vacillating-breathing. It also reproduces macroscopic behaviours like a shear thinning viscosity characteristic of complex fluids rheology. In addition, the model predicts a confinement law where the intrinsic viscosity varies as $\sim c^{1/3}$ for sufficiently strong confinements (c is the ratio of dumbbell size over the wall-to-wall distance). A transition from a tumbling regime towards a vacillating-breathing one is found. This mode is promoted further by confinement.

PACS - Low-Reynolds-number motions.
47.61.-k - Micro- and nano- scale flow phenomena.
47.57.Qk - Rheological aspects.

© Europhysics Letters Association 2007