Observations in comparison with simulations. Left panel: line-of-sight velocity determined with inversions of Hinode spectropolarimetric observations (adapted from van Noort et al. 2013), and the right panel displays the line-of-sight velocity resulting from an MHD simulation of a sunspot with a grid size of 16 km (adapted from Rempel 2012). Both panels display the spatial distribution of the velocity at the optical depth unity at continuum wavelengths.