Some Interesting Situations in the Hydrodynamics of Smectics and Cholesterics

We seek solutions to the hydrodynamical equations of smectics and cholesterics in three different circumstances: (a) When permeation is present we find that viscous heating plays a very important part, (b) An arbitrary but constant phase slippage can result in an AC Josephson effect, (c) Thermal expansion of the layers brings down the Binard threshold markedly.