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.
- Publication:
-
Physical Review E
- Pub Date:
- January 2017
- DOI:
- 10.1103/PhysRevE.95.012707
- arXiv:
- arXiv:1612.02274
- Bibcode:
- 2017PhRvE..95a2707Y
- Keywords:
-
- Physics - Fluid Dynamics;
- Condensed Matter - Soft Condensed Matter
- E-Print:
- Phys. Rev. E 95, 012707 (2017)