  The $L_\alpha$ phase of lipid bilayers is a fluid self-assembled state, key
to the formulation of cosmetics, detergents and pharmaceutics. Despite having
been extensively scrutinized in self-assembled phospholipid or surfactant
bilayers, the formation of a fluid $L_\alpha$ state has defied understanding in
mixtures of fatty alcohols, surfactants and water, where is viewed as the
essential step for the preparation of creamy dispersions. Here, atomistic
molecular dynamics simulations show the existence of a fluid bilayer in aqueous
mixtures of cetyl (C$_{16}$OH) and stearyl (C$_{18}$OH) alcohols, and
cetyl-trimethylammonium chloride (CTAC). These simulated bilayer systems
display not only a rich temperature phase diagram with many of the features
seen in experiments but carry also the unambigous signature of fluid bilayer
behavior.
