Dresden 2017 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 62: Complex Fluids and Soft Matter II (joint DY/CPP)

DY 62.3: Talk

Friday, March 24, 2017, 10:15–10:30, HÜL 186

Orientational order on surfaces - the coupling of topology, geometry and dynamics — •Axel Voigt, Michael Nestler, Ingo Nitschke, and Simon Praetorius — Institut für Wissenschaftliches Rechnen, TU Dresden, Germany

We consider the numerical investigation of surface bound orientational order using unit tangential vector fields by means of a gradient-flow equation of a weak surface Frank-Oseen energy. The energy is composed of intrinsic and extrinsic contributions, as well as a penalization term to enforce the unity of the vector field. Four different numerical discretizations, namely a discrete exterior calculus approach, a method based on vector spherical harmonics, a surface finite-element method, and an approach utilizing an implicit surface description, the diffuse interface method, are described and compared with each other for surfaces with Euler characteristic 2. We demonstrate the influence of geometric properties on realizations of the Poincare-Hopf theorem and show examples where the energy is decreased by introducing additional orientational defects.