Eur. Phys. J. E (2008) 25: 309-321
https://doi.org/10.1140/epje/i2007-10299-7

Regular Article

Two-dimensional fluctuating vesicles in linear shear flow

¹ II. Institut für Theoretische Physik, Universität Stuttgart, 70550, Stuttgart, Germany
² Istituto Applicazioni Calcolo, Consiglio Nazionale delle Ricerche (CNR), Via Amendola 122/D, 70126, Bari, Italy
³ Forschungszentrum Jülich GmbH, Institut für Festkörperforschung, 52425, Jülich, Germany

^* e-mail: finken@theo2.physik.uni-stuttgart.de
^** e-mail: a.lamura@ba.iac.cnr.it
^*** e-mail: useifert@theo2.physik.uni-stuttgart.de
^**** e-mail: g.gompper@fz-juelich.de

Received: 19 September 2007
Accepted: 15 February 2008
Published online: 9 April 2008

Abstract

The stochastic motion of a two-dimensional vesicle in linear shear flow is studied at finite temperature. In the limit of small deformations from a circle, Langevin-type equations of motion are derived, which are highly nonlinear due to the constraint of constant perimeter length. These equations are solved in the low-temperature limit and using a mean-field approach, in which the length constraint is satisfied only on average. The constraint imposes non-trivial correlations between the lowest deformation modes at low temperature. We also simulate a vesicle in a hydrodynamic solvent by using the multi-particle collision dynamics technique, both in the quasi-circular regime and for larger deformations, and compare the stationary deformation correlation functions and the time autocorrelation functions with theoretical predictions. Good agreement between theory and simulations is obtained.