  We conduct numerical simulations of axisymmetrical jets expanding into a
spherical AGB slow wind. The three-dimensional flow is simulated with an
axially symmetric numerical code. We concentrate on jets that are active for a
relatively short time. Our results strengthen other studies that show that jets
can account for many morphological features observed in planetary nebulae
(PNs). Our main results are as follows. (1) With a single jet's launching
episode we can reproduce a lobe structure having a `front-lobe', i.e., a small
bulge on the front of the main lobe, such as that in the PN Mz~3. (2) In some
runs dense clumps are formed along the symmetry axis, such as those observed in
the pre-PN M1-92. (3) The mass loss history of the slow wind has a profound
influence on the PN structure. (4) A dense expanding torus (ring; disk) is
formed in most of our runs. The torus is formed from the inflated lobes, and
not from a separate equatorial mass loss episode. (5) The torus and lobes are
formed at the same time and from the same mass loss rate episode. However, when
the slow wind density is steep enough, the ratio of the distance divided by the
radial velocity is larger for regions closer to the equatorial plane than for
regions closer to the symmetry axis. (6) With the short jet-active phase a
linear relation between distance and expansion velocity is obtained in many
cases. (7) Regions at the front of the lobe are moving sufficiently fast to
excite some visible emission lines.
