FLUCTUATION VISCOSITY OF LYOTROPIC SYSTEMS

The anomalous fluctuation contribution to viscosity coefficients eta(f l) of dilute lyotropic systems induced by fluctuations of membranes co nstituting the system is investigated. This contribution is determined by non-linear interaction of hydrodynamic modes with the bending mode , describing the relaxation of the shape of membranes, The explicit ex pressions for the eta(fl) can be obtained in the framework of Wyld dia gram technique by summation of a principal series of diagrams. There a re two regions of frequencies omega where eta(fl) behaves as \omega\-5 /3 and as \omega\-1/3 and is proportional to the concentration phi of surfactant molecules. In the low-frequency limit eta(fl) depends neith er on omega nor on phi and exceeds the viscosity of the pure solvent.