PANS Validation and Active Flow Control for a Simplified Truck Cabin

Paper i proceeding, 2017

Active Flow Control (AFC) can be applied using a various number of approaches. The general, yet ultimate, goal is to use a control strategy able to actively manipulate a separated flow. Reattachment or deflection of the shear layer is of main importance to enhance the aerodynamic performance of blunt and aerodynamic bodies. The paper presents a numerical and experimental study of the suppression of the recirculation bubble occurring at the side of a generic truck cabin (A-pillar separation) at Re = 5 × 10 5 . In this work the hybrid Partially Averaged Navier-Stokes (PANS) method was used. The aim of the present study is twofold: to validate the PANS method against in-house experiments and a resolved LES simulation, and to simulate the effect of an AFC on a heavily separated turbulent flow. Figure 1 shows the dimension of the computational and experimental domains (a and b) and the observed window in both experiments and simulations (c and d). The results show a good flow prediction by PANS even when the computational domain is drastically coarsened, Fig. 2. Velocity and Reynolds stress profiles, as well as modal and frequency analysis will be compared for a full validation. The AFC effect shows a drastic decrease of the side recirculation bubble, Fig. 3. The separation is observed to be receptive to the control and it locks to the specific actuation frequency when the latter is in the "receptive band". The flow reaches a frequency independent behaviour when the actuation frequency exceeds this range.