Drag Reduction by means of Active Flow Control Applied on a Generic Truck A-pillar: a Numerical and Experimental Study

Abstract: The overall goal of this thesis is to isolate and control the flow mechanism characterizing the flow separation occurring at the A-pillar of a truck. The study aims to gain knowledge of the flow physics of the separation mechanism, and to eventually suppress the afore mentioned separation by means of an Active Flow Control. State of the art unsteady numerical simulations and experiments are both employed to carry out this work. LES are performed at Re = 1 × 10 5 and post processed (by means of POD and FFT), to study the physics of the flow structures. Further, the hybrid PANS method is tested on several bluff body flows evaluating limits and qualities. The use of a hybrid technique as such is necessary to minimize the computer resources, while still being able to simulate a ”close to reality” Re. In the last part of the work, PANS are validated against wind tunnel experiments on a 3-D generic truck cabin. In the latter part PANS simulations are also employed to conduct an optimization study of the actuation frequency.