TY - JOUR

T1 - Layered structure of turbulent plane wall jet

AU - Wei, Tie

AU - Wang, Yanxing

AU - Yang, Xiang I.A.

N1 - Funding Information:
The authors are very grateful to Dr. J. G. Eriksson, Dr. R. I. Karlsson, and Dr. J. Persson for generously sharing their experimental data in ERCOFTAC (Case-55) http://cfd.mace.manchester.ac.uk/ercoftac/doku.php?id=cases:case055, and to Dr. I. Z. Naqavi for generously sharing his DNS data.
Publisher Copyright:
© 2021 Elsevier Inc.

PY - 2021/12

Y1 - 2021/12

N2 - This paper investigates the layered structure of a turbulent plane wall jet at a distance from the nozzle exit. Based on the force balances in the mean momentum equation, the turbulent plane wall jet is divided into three regions: a boundary layer-like region (BLR) adjacent to the wall, a half free jet-like region (HJR) away from the wall, and a plug flow-like region (PFR) in between. In the PFR, the mean streamwise velocity is essentially the maximum velocity, and the simplified mean continuity and mean momentum equations result in a linear variation of the mean wall-normal velocity and Reynolds shear stress. In the HJR, as in a turbulent free jet, a proper scale for the mean wall-normal flow is the mean wall-normal velocity far from the wall and a proper scale for the Reynolds shear stress is the product of the maximum mean streamwise velocity and the velocity scale for the mean wall-normal flow. The BLR region can be divided into four sub-layers, similar to those in a canonical pressure-driven turbulent channel flow or shear-driven turbulent boundary layer flow. Building on the log-law for the mean streamwise velocity in the BLR, a new skin friction law is proposed for a turbulent wall jet. The new prediction agrees well with the correlation of Bradshaw and Gee (1960) over moderate Reynolds numbers, but gives larger skin frictions at higher Reynolds numbers.

AB - This paper investigates the layered structure of a turbulent plane wall jet at a distance from the nozzle exit. Based on the force balances in the mean momentum equation, the turbulent plane wall jet is divided into three regions: a boundary layer-like region (BLR) adjacent to the wall, a half free jet-like region (HJR) away from the wall, and a plug flow-like region (PFR) in between. In the PFR, the mean streamwise velocity is essentially the maximum velocity, and the simplified mean continuity and mean momentum equations result in a linear variation of the mean wall-normal velocity and Reynolds shear stress. In the HJR, as in a turbulent free jet, a proper scale for the mean wall-normal flow is the mean wall-normal velocity far from the wall and a proper scale for the Reynolds shear stress is the product of the maximum mean streamwise velocity and the velocity scale for the mean wall-normal flow. The BLR region can be divided into four sub-layers, similar to those in a canonical pressure-driven turbulent channel flow or shear-driven turbulent boundary layer flow. Building on the log-law for the mean streamwise velocity in the BLR, a new skin friction law is proposed for a turbulent wall jet. The new prediction agrees well with the correlation of Bradshaw and Gee (1960) over moderate Reynolds numbers, but gives larger skin frictions at higher Reynolds numbers.

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U2 - 10.1016/j.ijheatfluidflow.2021.108872

DO - 10.1016/j.ijheatfluidflow.2021.108872

M3 - Article

AN - SCOPUS:85117132209

VL - 92

JO - International Journal of Heat and Fluid Flow

JF - International Journal of Heat and Fluid Flow

SN - 0142-727X

M1 - 108872

ER -