Regensburg 2010 – scientific programme

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BP: Fachverband Biologische Physik

BP 26: From Single-Molecule to Tissue Dynamics

BP 26.11: Talk

Thursday, March 25, 2010, 17:00–17:15, H43

Antisymmetric stress and the role of angular momentum conservation in complex fluids. — •Sebastian Fürthauer, Stephan Grill, and Frank Jülicher — Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Str. 38, 01187 Dresden, Germany

The stress tensor of a Newtonian fluid is symmetric in the hydrodynamic limit. However, in complex fluids, such as nematic liquid crystals, the director field can exert a torque if it is locally rotated away from its undistorted configuration. This produces a reactive antisymmetric contribution to the stress tensor. Here, we provide the derivation of a hydrodynamic theory for a complex fluid based on identifying the entropy production rate from the rate of change of the free energy. Analyzing the angular momentum balance, reveals that an additional dissipative contribution to the antisymmetric stress exists. We obtain an expression for the antisymmetric dissipative stress by expanding thermodynamic fluxes in terms of thermodynamic forces, which is crucial in understanding the non-equilibrium dynamics of chiral complex fluids, such as the acto-myosin cytoskeleton or a fluid driven by beating cilia.