Physics of outflows from active galactic nuclei

Outflows participating in defining the various types of morphologies and features observed in Active Galactic Nuclei (AGN) are discussed. Possible interpretations are suggested of structures observed at radio frequencies (non-thermal continuum radiation) and optical frequencies (continuum and emission line radiation) in terms of results from numerical simulations of outflow propagation and their analytical physical explanation. The conclusion is that we have already reached a good qualitative knowledge of the dynamic effects which shape AGN's structures; the quantitative estimate of their relative importance and conditions of occurrence still awaits a better study of the nonlinear processes in astrophysical conditions and more observational data to determine the values of the physical parameters. (author). 2 figs., 22 refs