Journal of Non-Newtonian Fluid Mechanics, Vol.165, No.1-2, 32-44, 2010
Structure and rheology of fiber-laden membranes via integration of nematodynamics and membranodynamics
This paper presents a study of the structure and dynamics of rigid fiber-laden deformable curved fluid membranes based on an viscoelastic model that integrates the statics of anisotropic membranes, the planar nematodynamics of fibers and the dynamics of isotropic membranes. Fiber-laden membranes arise frequently in biological systems, such as the plant cell wall and in protein-lipid bilayers. Based on the membrane's force and torque balance equations and the fiber's balance of molecular fields, a viscoelastic anisotropic model that provides the governing equations for the membrane's velocity and curvature and the fiber structure (fiber orientation and order) is found. A Helmholtz free energy that incorporates the tension/bending/and torsion membrane elasticity, the Landau-de Gennes fiber ordering, and fiber order-membrane curvature interactions is used to derive elastic moments, torques,and stresses. The corresponding viscous stresses and moments include the Boussinesq-Scriven contributions as well as bending, torsion, and rotational dissipation. A spectral decomposition leads to the main viscoelastic material functions for anisotropic fluid membranes. Applications of the rheological model to cylindrical growth and cylindrical axial stretching show that competing curvo-phobic, curvo-philic interactions under extensional flow predict transitions between axial and azimuthal fiber arrangements. of interest to cellulose fiber orientation in plant morphogenesis. (C) 2009 Elsevier B.V. All rights reserved.
Keywords:Anisotropic membrane model;Viscoelastic shape equation;Fiber-laden membranes;Curvature and membrane velocity-driven nematic self-assembly