A semiclassical fluiddynamical model based on an usual scaling approximation (SCA) is extended to investigate the role of one and two-body dissipation in the widths of nuclear collective modes. The competition between one and two-body viscosity in: i) the collisionless (elastic) limit; ii) the hydrodynamical case and iii) the general viscoelastic regime is examined over the whole range of nuclear collision time scales. Numerical solutions are investigated for the first magnetic 2-twist mode in 2~

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We investigate the fluiddynamical description of nuclear motion induced by the variational procedure in the presence of one-and two-body dissipation. The equation of motion for the scaling field is established for an abnormal parity mode in a nucleus with a Wood-Saxon density. The local relaxation time can be computed as a function of the distance to the nuclear center, as well as the two-body viscosity. The hydrodynamical and the viscoelastic regimes are specifically examined. It is found that the later appears more appropriate to fit the energy, frequency and time scales of actual nuclei.