Adaptive propagation grids calculated for the double-clump spherically symmetrical model. We have plotted only one quadrant in the zero plane. The red “circle” is the central star, blue circles represent the model grid shells and the grey and the blue Cartesian grid represent propagation grid. It is clear that in the area of the clump the density of the propGrid is much larger. Left: Octgrid, basic grid: 50³, 10⁶ virtual points, right: one-level subgrid, basic grid: 10³, 10⁶ virtual points.