Final Report Summary - CGCOMPLEXFLUIDFLOW (Systematic and thermodynamically consistent coarse graining the flow of complex fluids)
In this project, we investigate coarse-graining approaches for two microscopic model systems of nematic liquid crystals: the Lebwohl-Lasher spin lattice system as well as an off-lattice systems of rigid ellipsoids interacting via the Gay-Berne potential. As collective variable, we choose the orientational order parameter tensor. A cornerstone of the macroscopic theory of liquid crystals is the Landau-de Gennes free energy.
Rather than postulating the Landau-de Gennes free energy, we were able to establish a link between this effective free energy and a large deviation function. Using Chernoff's formula allows us to determine the latter numerically and to reduce the numerical uncertainties compared to earlier approaches. Furthermore, we showed for the Lebwohl-Lasher model the equivalence of the projection operator approach to a more traditional, Kirkwood-like method of coarse graining. Special emphasis we paid on the resulting time correlation functions of fluctuations that play a central part in determining macroscopic properties. Interestingly, we find propagating modes and long-time tails in the angular momentum correlations.
More information and the corresponding publications can be found under http://www.personal.reading.ac.uk/~sg906606/CGcomplexfluidflow.html or directly contacting Patrick Ilg via email: p.ilg@reading.ac.uk.