A single spanwise array of cylinders was used to perturb a zero pressure gradient turbulent boundary layer (Reτ=2500). The cylinder height was H/δ=0.2 (H+=500) with aspect ratio (height/diameter) of AR=4, and four cases were studied with cylinder spacing from 0.2δ to 0.8δ. Streamwise-spanwise planes were measured by particle image velocimetry (PIV) up to 7δ downstream at a wallnormal location of z+=300. The 0.6δ case, which matched the dominant spanwise mode in the unperturbed flow, showed the most stable downstream organization which persisted beyond 7δ. The cylinders were observed to sometimes enhance the organization of existing packets and to generally redirect packets into the spanwise location midway between cylinders. Approaching packets lost their organization immediately downstream of the 0.2δ array but regained it downstream, suggesting that the outer layer organization propagated inward into the log region.
|Original language||English (US)|
|Title of host publication||International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2013|
|State||Published - 2013|
|Event||8th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2013 - Poitiers, France|
Duration: Aug 28 2013 → Aug 30 2013
|Name||International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2013|
|Other||8th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2013|
|Period||8/28/13 → 8/30/13|
Bibliographical noteFunding Information:
The authors gratefully acknowledge support from the U.S. National Science Foundation through Grant CBET-0933341.