The Instability of the Flow in a Nematic Liquid Crystal MBBA

The electrohydrodynamic effect is studied on the nematic liquid crystal MBBA. The flow velocity, the forming time of the characteristic flow, its recovery time and the fluctuation of the transmission of light are observed as functions of applied voltage V . The former two quantities show the existence of the three regions in which they are functionalized with the dimensionless parameter in the form ( k -1) n : for example n =0.90, 1.38 and 1.75 for the reciprocal of the forming time. Where k = V / V c and V c is the critical voltage at which the flow begins to from the Williams domain. The recovery time shows the existence of several regions. An analogy of k to the Δ T / Δ T c is suggested, where Δ T and Δ T c is the thermal gradient and its critical value, respectively, in the case of the thermally excited liquid.