Electrohydrodynamic Instability Chevron Mode

Orientational oscillations of the director in the chevron mode occur in the phase with the applied field [74] (details of the optical investigations of the chevron structure are also given in [75]). 

The chevron appearance is described by means of a time-dependent system of linearized equations of nematodynamics in an electric field, which could be reduced as follows  

FIGURE 5.10. Electrohydrodynamic instabilities in nematic liquid crystal with homogeneous initial orientation in the high-frequency regime (a lJc)- (a) Domains when the voltage is slightly above the threshold voltage and (b) the Chevron pattern. 

The threshold voltage of the instability is found from (5.39) as the condition for periodicity of the solutions (p t) and Q t) with the period equal to that of the external field E t) [67-73]. 

The investigation of (5.39) for the sinusoidal [67, 68] and square wave [69, 70, 73] forms of the external field E t) leads to the following two characteristic regimes of the instability. 

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