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\textbf{\citet{2010A&A...511A..42B} presented simulations with a time variable launching speed, where blobs of material are emitted into the jet every few months or years. Their jet has a radial velocity profile that avoids the growth of random perturbations at the jet boundary and that is compatible with the expected magnetic fields in the environment of young stars. In these simulations faster material catches up with slower, previously emitted matter and shocks form that travel along the jet. Since material is launched almost continuously, the first interaction often takes place fairly close to the star and the simulations show a X-ray emission region only about 100~AU from the star, which fluctuates in luminosity but is present at all times. This region represents only a small fraction of the total simulated X-ray emission from the jet \citep{2010A&A...517A..68B}. }  \citet{2011ApJ...737...54B} numerically simulated stationary X-ray shocks. To do so, they impose a rigid nozzle with a radius \textbf{between 15 and 200 AU} and inject a flow of plasma with an \textbf{intially} flat velocity \textbf{and density} profile along the jet axis. The regiosn region  that accelerates the mass at the bottom of the nozzle is not part of the model, but given the large radius, both disk wind and stellar wind might contribute in such a scenario. \citet{2011ApJ...737...54B} find that \textbf{a denser layer forms on the walls of the nozzle and that this perturbation travels inward. When this feature reaches the axis of symmetry} a diamond-shaped shock forms at a height \textbf{of 200-300 AU for a nozzle with a radius of 100~AU} with temperatures high enough to explain the X-ray emission from HH~154. \textbf{This model has not been applied to DG Tau, but might provide a viable explanation for the emission in DG Tau, too, if the shape and size of the nozzle is tuned properly.} In contrast to that work, we do not impose rigid boundaries that collimate the flow, but instead prescribe an external pressure profile and then calculate the position of the boundary between the inner wind and the external medium. The setup of \citet{2011ApJ...737...54B} is well-suited to study regions at \textbf{a distance of 200-300~AU} from the star, but in this article we concentrate on the inner region, where the outflow is not yet parallel to the jet axis and stellar and disk outflows have different velocities. Thus, we start with a spherical flow from the stellar surface and explain how a shock can be caused by the recollimation of the stellar outflow due to pressure from the outer disk winds.   \textbf{\citet{2012MNRAS.422.2282K} developed a model for this geometry in the context of relativistic jets. Here we apply this model to stellar jets.}