Euler-Poincar\'e approaches to nematodynamics
  Nematodynamics is the orientation dynamics of flowless liquid-crystals. We show how Euler-Poincar\'e reduction produces a unifying framework for various theories, including Ericksen-Leslie, Luhiller-Rey, and Eringen's micropolar theory. In particular, we show that these theories are all compatible with each other and some of them allow for more general configurations involving a non vanishing discination density. All results are also extended to flowing liquid crystals. 
Fran\c{c}ois Gay-Balmaz, Tudor S. Ratiu, Cesare Tronci
cond-mat.soft nlin.CD