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Tumbling of viscous vesicles in a linear shear field near a wall♣

V. VITKOVA1,* , G. COUPIER2, M.-A. MADER2, B. KAOUI2, C. MISBAH2, T. PODGORSKI2

Affiliation

  1. Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd., 1784 Sofia, Bulgaria
  2. Laboratoire de Spectrométrie Physique, 140 Avenue de la Physique, 38402 St-Martin-d’Hères, France

Abstract

The dynamics of lipid vesicles enclosing a viscous polymer solution is studied in a simple shear flow near a wall. The ratio between the internal fluid viscosity and the one of the outer aqueous solution is chosen to be above the tank-treading-to-tumbling transition for all analyzed vesicles. A clear influence of the presence of the wall on the tumbling motion of vesicles has been detected. In the entire range of applied shear rates, pure tumbling has not been observed due to the high density difference between the internal fluid and the suspending medium, keeping vesicles close to the wall. The strong deformability of their membranes, coupled to the high viscosity ratios, leads to a periodic modulation of the vesicle shape, with a periodicity correlated to the shear rate of the hydrodynamic flow and amplitudes depending on the vesicle's deflation. This shape modulation is coupled to a rolling motion of the vesicles..

Keywords

Giant vesicles, White blood cells, Shear flow, Deformability.

Submitted at: Nov. 5, 2008
Accepted at: Sept. 9, 2009

Citation

V. VITKOVA, G. COUPIER, M.-A. MADER, B. KAOUI, C. MISBAH, T. PODGORSKI, Tumbling of viscous vesicles in a linear shear field near a wall♣, Journal of Optoelectronics and Advanced Materials Vol. 11, Iss. 9, pp. 1218-1221 (2009)