Horizontal velocities (computed between 09 and 16 UT) over an Hα image (16:42 UT). Yellow contours indicate the supergranules. The black arrows indicate flows going through the filament channel from the north towards the south in the eastern part or from west to east in the northern part, perpendicular to the filament axis. The red arrows indicate flows perpendicular to the filament with some whirls. The large west-east flows on the western side of the filament are stopped at the western edge of the filament channel.