TY - JOUR

T1 - Prediction of drag reduction effect by streamwise traveling wave-like wall deformation in turbulent channel flow at practically high Reynolds numbers

AU - Nabae, Yusuke

AU - Kawai, Ken

AU - Fukagata, Koji

N1 - Funding Information:
The authors are grateful to Drs. Shinnosuke Obi and Keita Ando (Keio University) for fruitful discussions. This work was supported through JSPS KAKENHI grant numbers 25420129 and 18H03758 by Japan Society for the Promotion of Science (JSPS).
Funding Information:
The authors are grateful to Drs. Shinnosuke Obi and Keita Ando (Keio University) for fruitful discussions. This work was supported through JSPS KAKENHI grant numbers 25420129 and 18H03758 by Japan Society for the Promotion of Science (JSPS).

PY - 2020/4

Y1 - 2020/4

N2 - A fully developed turbulent channel flow controlled by traveling wave-like wall deformation under a constant pressure gradient condition is studied numerically and theoretically. First, direct numerical simulation (DNS) at three different friction Reynolds numbers, Reτ=90, 180, and 360, are performed to investigate the modification in turbulence statistics and their scaling. Unlike the previous study assuming a constant flow rate condition, suppression of the quasi-streamwise vortices is not observed in either drag decrease cases or drag increase cases. It is found in the drag reduction case, however, that the periodic component of the Reynolds shear stress (periodic RSS) is largely negative in the viscous sublayer and the buffer layer. For the maximum drag reduction case, the set of control parameters is found to be identical in wall units regardless of the Reynolds number, and the resulting mean velocity profiles are also observed to be approximately similar even with an additional case of Reτ=720. Based on this scaling, we propose a semi-empirical formula for the mean velocity profile modified by the present control. With this formula, about 20%−25% drag reduction effect is predicted even at practically high Reynolds numbers, Reτ∼105−106.

AB - A fully developed turbulent channel flow controlled by traveling wave-like wall deformation under a constant pressure gradient condition is studied numerically and theoretically. First, direct numerical simulation (DNS) at three different friction Reynolds numbers, Reτ=90, 180, and 360, are performed to investigate the modification in turbulence statistics and their scaling. Unlike the previous study assuming a constant flow rate condition, suppression of the quasi-streamwise vortices is not observed in either drag decrease cases or drag increase cases. It is found in the drag reduction case, however, that the periodic component of the Reynolds shear stress (periodic RSS) is largely negative in the viscous sublayer and the buffer layer. For the maximum drag reduction case, the set of control parameters is found to be identical in wall units regardless of the Reynolds number, and the resulting mean velocity profiles are also observed to be approximately similar even with an additional case of Reτ=720. Based on this scaling, we propose a semi-empirical formula for the mean velocity profile modified by the present control. With this formula, about 20%−25% drag reduction effect is predicted even at practically high Reynolds numbers, Reτ∼105−106.

KW - Drag reduction

KW - High Reynolds number

KW - Theoretical prediction

KW - Turbulent channel flow

KW - Wall deformation

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U2 - 10.1016/j.ijheatfluidflow.2020.108550

DO - 10.1016/j.ijheatfluidflow.2020.108550

M3 - Article

AN - SCOPUS:85078566193

VL - 82

JO - Heat Fluid Flow

JF - Heat Fluid Flow

SN - 0142-727X

M1 - 108550

ER -