Twin bars (d)

In addition to the drag reduction, the damping of lift fluctuation is also desired which might be achieved by configurations that allow contact between the top and bottom end of the Gurney-flap. Therefore the next configuration consists of two vertical bars located parallel with spacing $0.6h$ behind the flap. The height of the first bar is $0.6h$ whereas the second only measures $0.4h$ similar to the investigations of Bechert et al. [7]. The depth of all bars is $0.2h$.

Similar to the splitter-plate the twin bar configuration has almost no effect on the mean lift. The drag induced by the Gurney-flap is however reduced by $36\%$. At the same time, lift fluctuations are reduced by a factor of $6$. Compared to experiments in table , lift and drag show qualitatively coincident behavior but the reduction of drag is overpredicted in the computation.