J. Verhas, C. Papenfuss and W. Muschik
A simplified thermodynamic theory for biaxial
nematics using Gyarmati's principle
Mol. Cryst. Liq. Cryst. 215, 1992, 313-321
Gyarmati's variational principle of thermodynamics is used to derive
the equilibrium conditions as well as the equations of motion for
biaxial nematic liquid crystals. From the equations of motion the
nonequilibrium stress tensor is derived. The resulting equations are
much easier than in the case of uniaxial nematics. This is probably a
consequence of the fact that the state space can be chosen in such a
way that no constraints for the generalized directors and their
gradients have to be taken into account.