Global view of the time-averaged surface density of pebbles in the simulation MspE0_M1.5St0.089 without (top) and with (bottom) the addition of random noise to the gas velocities near the outer truncation of the superparticle domain. The bottom panel correctly recovers the underdense perturbation created by pebble accretion and pebble dynamics near the planet while avoiding the disturbances spreading from the outer boundary.