Threshold structural transition in nematics in homogeneous ultrasonic fields

The effect of molecule reorientation in a homeotropically aligned layer of a nematic liquid crystal under the action of a transversely homogeneous ultrasonic wave is studied, and its description in terms of the new theoretical model based on the nonequilibrium thermodynamics and nonlinear hydrodynamics of liquid crystals is experimentally verified. It is shown that the effect is of a threshold character, the critical particle velocity is inversely proportional to the layer thickness, and the stationary distortion of macrostructure is uniform along the layer.