Excitation of stripe domain patterns by propagating acoustic waves in an oriented nematic film

Stripe domain patterns have been observed in a nematic liquid crystal film excited by ultrasonic waves propagating in a sandwiched glass-nematic-glass medium. The effect was found to be due to molecular reorientation induced by acoustic streaming in the nematic film. Based on a simple fluid dynamical model, we calculated the propagating acoustic modes, their nonlinear mixing which causes acoustic streaming, and the resultant shear flow reorientation of the director which produces the birefringent stripe patterns. Our calculations show quantitative agreement with the measured acoustic modes and the observed stripe domain patterns.