title: Acoustic streaming in two-dimensional freely suspended smectic liquid crystal films.
abstract: We study horizontal streaming excited by means of a low-frequency and low-intensity acoustic wave in 2D freely suspended films of thermotropic smectic liquid crystals. Acoustic pressure induces fast periodic transverse oscillations of the film, which produce in-plane stationary couples of vortices slowly rotating in opposite directions owing to hydrodynamic nonlinearity. The parameters of the vortices are measured using a new method, based on tracking solidlike disk-shaped islands. The horizontal motion occurs only when the amplitude of the acoustic pressure exceeds the threshold value, which can be explained by Bingham-like behavior of the smectic film. The measurements above threshold are in good agreement with existing theoretical predictions. We demonstrate experimentally that in-plane flow is well controlled by changing the acoustic pressure, excitation frequency, and geometry of the film. The observations open the way to using the phenomenon in nondisplay applications.
authors.affiliation: Landau Institute for Theoretical Physics of the Russian Academy of Sciences, 142432 Akademica Semenova av. 1-A, Chernogolovka, Russia.|Shubnikov Institute of Crystallography of Federal Scientific Research Center "Crystallography and Photonics" of the Russian Academy of Sciences, 119333 Leninsky pr. 59, Moscow, Russia.
authors.forename: S V
authors.initials: SV
authors.lastname: Yablonskii
authors.affiliation: Shubnikov Institute of Crystallography of Federal Scientific Research Center "Crystallography and Photonics" of the Russian Academy of Sciences, 119333 Leninsky pr. 59, Moscow, Russia.|Moscow Institute of Physics and Technology, 141700 Institutskiy per. 9, Dolgoprudny, Russia.
authors.forename: N M
authors.initials: NM
authors.lastname: Kurbatov
authors.affiliation: Landau Institute for Theoretical Physics of the Russian Academy of Sciences, 142432 Akademica Semenova av. 1-A, Chernogolovka, Russia.
authors.forename: V M
authors.initials: VM
authors.lastname: Parfenyev