The dynamical processes of the interaction of slow wind beyond Red Giant phase with fast wind of central star of nebula are evaluated. The mechanism of interaction stellar wind model (ISW) is found to be responsible for producing a relatively dense shell of gas which increases in mass and radius at a constant rate. Both slow wind and superwind are assumed to be time independent and radial density is calculated at initial time t_o ~ 60 yrs with the fast wind velocity (v ≈ 1000 km/s). The results showed that, at the outer rim of super wind region, a small density hump appears due to the relative velocity between slow winds and central star winds, in a good agreement with the previous models. The dynamical requirements of the observed expansion of planetary nebulae can be satisfied by the mechanism of interacting stellar wind model with reasonable mass loss rate from central star.