We evaluate the pre-determined control with temporally- and spatially-periodic spanwise velocity inputs at the wall in a fully developed two-dimensional turbulent channel flow. The spatially-periodic control generally achieves better performance than the temporally-periodic control, the latter of which is called conventionally the spanwise wall-oscillation control. To analyze the drag reducing mechanisms, we focus on the near-wall structures such as quasi-streamwise vortices and low-speed streaks. As a result, it is found that the drag is reduced through the modified spatial phase-relationship between the streamwise vortex and the low-speed streak.
|Number of pages||6|
|Publication status||Published - 2009|
|Event||6th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2009 - Seoul, Korea, Republic of|
Duration: 2009 Jun 22 → 2009 Jun 24
|Conference||6th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2009|
|Country/Territory||Korea, Republic of|
|Period||09/6/22 → 09/6/24|