Flow Features in a Fully Developed Ribbed Duct Flow as a Result of MILES

The present contribution describes the topology associated with the turbulent flow in a square duct partially blocked by a rib of square section mounted on a single wall. The flow is simulated by means of a MILES method and the resulting velocity fields are analysed using the concepts of stream surface, vortex core detection, wall streamline and bifurcation line. Instantaneous and time averaged coherent structures are extracted applying the second scalar invariant of the velocity gradient tensor (so-called $Q$ criterion), respectively, to the instantaneous and time averaged velocity fields. This postprocessing reveals significant 3D effects induced by the geometry, namely the influence of the side walls, which is clearly identified. The combination of the different visualisation techniques offers a complement to the standard representation based on Eulerian statistics and contributes to a deeper understanding of this complex flow.