TAF PUBLISHING

The performance of three different numerical methods for predicting the large separated flow over a hump model and its control using steady suction and techniques is investigated. Unsteady Reynolds Averaged Navier-Stokes (URANS), Detached Eddy Simulation (DES) and Delayed Detached Eddy Simulation (DDES) approaches are developed and applied to determine the proficiency of these approaches in predicting such degree of separation and assess their applicability to capture the turbulent flow structures in the separated flowfield. Active flow control techniques are applied by means of two-dimensional slot located at x/c ≈ 0.65 along the model spanwise with an opening of 0.00187c, directly upstream on the concave surface. The novelty of the present work is that the dynamic grid technique is formulated to model the repeated motion of the synthetic jet membrane instead of using the oscillating boundary conditions at the jet exit. Dynamic grid is found to be useful in providing more insight into the physical mechanism that drive the interface between the plenum flow and separated boundary layer flow. The numerical results obtained from the baseline and controlled cases are validated against the measurements and compared with published numerical results in terms of mean flow quantities. Despite the fact that URANS and DES methods provide good agreement with the measurements for the uncontrolled and steady suction controlled cases, only DES showed the flow unsteadiness, however the DDES method failed to predict the mean flow quantities or the turbulent flow features. The dynamic grid technique successfully simulated the cavity flow, showed up the existence of two counter rotating vortices inside the plenum move up and down during the control cycle and finally energized the boundary layer in the separated flow region.