2D Periodic Hill

Underlying Flow Regime 3-30

Cross-Comparison of Experiments

The 2D PIV results were checked with 1D LDA measurements. A satisfactory compliance was found as can be seen in the following figures (Re=10,600) [Rapp et al. (2009), Rapp (2009)].

The PIV field data and the point by point LDA measurements show an excellent accordance. The mean velocity component in the x-direction and the streamwise Reynolds stress show only minor deviations that can be traced back to the measurement procedure. As the LDA data could only be acquired by measuring the particular points periodically and at different instants of time, the profiles turn out to be rougher than the PIV data.

Cross-Comparison of CFD Calculations

Comparison of predictions by LESOCC and MGLET based on the streamwise velocity profiles at four different locations ($x / h = 0.5$, $2$, $4$, and $6$) and two different Reynolds numbers, i.e.\ Re = 2800 (case 4 and 5) and 5600 (case 7 and 8, see Table 1)

Comparison of CFD Calculations with Experiments

The experimental data at Reynolds number 10,600 are compared with LES results by LESOCC [Breuer et al. (2009), Rapp et al. (2009)]. The following figures show averaged velocity profiles for <u>/u_b at four streamwise positions.

The agreement between the predicted and the measured mean streamwise velocity component in the x-direction is very good. Minor deviations can be found in the shear layer (slightly higher velocities in the experiment) and in the post-reattachment zone. The vertical velocity component <v>/u_b is about one order of magnitude smaller than the streamwise component and yet more sensitive. However, the measurements comply with the simulation results in a fully satisfactory manner. The largest deviations are found at x/h=2.

The measured and the predicted Reynolds shear stress show a close agreement at the different x/h-positions. The location of the experimental peak values and their distributions are in close accordance with the predictions. Solely at x/h=6 a slightly higher stress was found in the experimental data.