  Recent HST observations suggest that the NLR in Seyfert Galaxies can be the
result of interaction between jet and external inhomogeneous medium; following
this suggestion we perform numerical simulations considering the impact of a
radiative jet on a dense cloud. We approach the problem adopting a
hydrodynamical code, that consents us to study in detail the jet hydrodynamics,
while we choose a more simplified treatment of radiative processes, in order to
give a qualitatively good interpretation of the emission processes. Our three
main purposes are: i) to reproduce in our simulations the physical conditions
observed in the NLR of Seyfert Galaxies, ii) to obtain physical constraints of
the jet parameters and iii) to study the jet capability to photoionize the
surrounding medium.
