and Papaloizou, 2003). Thus, if the Lindblad torque dominates, we expect the planets to have the same evolution, just a factor of 2 slower. If the corotation torque dominates, the change in the dynamics can not be [**trivially**]{} reduced to a simple scaling on time. Fig. \[smalldisk\] shows the result. The black curves show the evolution of Jupiter and Saturn in the nominal gas disk. The grey curves show the evolution of the planets in a disk with half the initial density. In plotting this second pair of curves, the time-span measured relative to the release time (400 orbits) has been divided by two. The black and grey curves superpose almost perfectly. This [**suggests that the Lindblad torque is stronger than the corotation torque**]{}.

Dependence on the simulation’s technical parameters {#tech_params}
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Before proceeding further with our exploration of the dynamical evolution of Jupiter and Saturn, we check the impact of some technical parameters used in the simulation: specifically the smoothing length for the gravitational potential and the grid resolution for the disk.

As usual in 2 dimensional hydro-dynamical simulations, the equations of motions are regularized in the vicinity of the planet by modifying the gravitational potential energy $U(\Delta)=-(M_p m)/\Delta$ 