T. Schilling, O.Theissen, and G. Gompper

We investigate the dynamical behavior of lamellar phases in ternary amphiphilic systems of water, oil and amphiphile. The interaction between neighboring amphihpilic monolayers is decribed by the steric interaction, which arises from the entropy loss due to the confinement of membrane fluctuations in a stack. The dynamics of the system is determined by the hydrodynamics of the fluid layers. Relaxation rates are calculated for arbitrary wave vectors q parallel and perpendicular to the average monolayer plane. We find a complex crossover behavior from a q**2-law for small parallel wave vectors to a q**3-law for large q. The relevance of our results for the interpretation of dynamic scattering experiments is discussed.