Comparison of large-scale flow patterns resulting from a combination of geometric constraints and blockage of heat flux in the photosphere. Panel (a) shows the flow pattern developing around a cylinder with 8 Mm radius due to the imposed geometric constraint. Panel (b) shows the flow patterns developing in response to switching off the radiative cooling in the region R < 8 Mm. Panels (c) and (d) show flows around cone-shaped obstacles with different opening angles, which result from a combination of geometric and thermal effects.