Effects of flow on the dynamics of a ferromagnetic nematic liquid crystalPotisk, Tilen (Avtor)
Pleiner, Harald (Avtor)
SvenÅ¡ek, Daniel (Avtor)
Brand, Helmut R. (Avtor)
condensed matter physicsnematic liquid crystalsferromagnetic liquid crystalsfluid dynamicscomplex fluidsWe investigate the effects of flow on the dynamics of ferromagnetic nematic liquid crystals. As a model we study the coupled dynamics of the magnetization, M, the director field, n, associated with the liquid crystalline orientational order and the velocity field v. We evaluate how simple shear flow in a ferromagnetic nematic is modified in the presence of small external magnetic fields and we make experimentally testable predictions for the resulting effective shear viscosity: an increase by a factor of two in a magnetic field of about 20 mT. Flow alignment, a characteristic feature of classical uniaxial nematic liquid crystals, is analyzed for ferromagnetic nematics for the two cases of a magnetization in or perpendicular to the shear plane. In the former case we find that small in-plane magnetic fields are suffcient to suppress tumbling and that thus the boundary between flow alignment and tumbling can be controlled easily. In the latter case we furthermore find a possibility of flow alignment in a regime for which one obtains tumbling for the pure nematic component. We derive the analogues of the three Miesowicz viscosities well-known from usual nematic liquid crystals, corresponding to nine different configurations. Combinations of these can be used to determine several dynamic coeffcients experimentally.20182018-06-21 11:38:52Neznano101615sl