Surface density deviation heat maps similar to Fig. 3, but for FARGO simulations at a resolution of 256 × 256 on an arithmetic grid (top) and at 456 × 256 on a logarithmic grid (bottom). Top: Setup that reproduces the results of SK03 (see Fig. 6 therein). The flip from a leading to trailing spiral is visible in the middle two panels, before it disappears into a single leading spiral. Bottom: Setup that is equivalent to our fiducial PLUTO model, and behaves very similar to our results in Fig. 3. Here, spirals develop earlier and the initial flip is short-lived and closer to the inner boundary.