Shape optimization of an active and a passive drag-reducing device on atwo-dimensional D-shaped bluff body is performed. The two devices are: Coandaactuator, and randomly-shaped trailing-edge flap. The optimization sequence isperformed by coupling the genetic algorithm software DAKOTA to the meshgenerator Pointwise and to the CFD solver OpenFOAM. For the the active devicethe cost functional is the power ratio, whereas for the passive device it isthe drag coefficient. The optimization leads to total power savings of $\approx70\%$ for the optimal Coanda actuator, and a 40\% drag reduction for theoptimal flap. This reduction is mainly achieved through streamlining the baseflow and suppressing the vortex shedding. The addition of either an active or apassive device creates two additional smaller recirculation regions in the basecavity that shifts the larger recirculation region away from the body andincreases the base pressure. The results are validated against more refinedURANS simulations for selected cases.
展开▼
