Azimuthally averaged surface density profiles from all disc models computed once each run had evolved for ~49 000 yr after the value of K was increased from 6 to 30 in Eq. (4). The planet positions are indicated by the filled circles. Note that the inner boundary condition influences the surface density profiles close to the inner boundary. The profiles shown for each run correspond to the right-hand-most midplane density contours shown in Fig. 5.