Thermally excited flow in a microsized liquid crystal cavity

Nonmechanical pumping has been investigated as a liquid crystal device, based on the interplay between the structure of liquid crystal phase (director field), velocity field, heat flow and electric field. The mesogen occupies a homogeneously-aligned liquid crystal (HALC) cavity, delimited by two infinitely long, charged horizontal and coaxial cylinders. A uniform heat flow is applied radially, from the inner cylinder to the outer (colder) one, kept at a constant temperature; the radially directed electrostatic field results from the two electric double layers, i.e. shielding cylindrical layers that are naturally created within the liquid crystal (LC) near a charged surface. Calculations, based on the appropriate nonlinear extension of the classical Ericksen–Leslie theory, show that, under the influence of the uniform heat flow, the HALC material starts moving in the horizontal direction. After switching off the heat flow, the HALC material settles down to rest, and the temperature field across the LC cavity finally drops to the value imposed on the outer (colder) boundary. As for the nematogenic material, we have considered the HALC cavity to be occupied by 4-n-pentyl-40-cyanobiphenyl, and investigated the role of the bounding cylinders in the evolution processes of both the velocity and the thermomechanical shear stress tensor component to their equilibrium distributions across the cavity, for one heating regime and a number of anchoring conditions.