scholarly journals OSCILLATORY BOTTOM BOUNDARY LAYER BY LOW-REYNOLDS NUMBER TURBULENCE MODEL

1988 ◽  
Vol 1 (21) ◽  
pp. 55
Author(s):  
Toshiyuki Asano ◽  
Hitomi Goda ◽  
Yuichi Iwagaki
Keyword(s):  
Reynolds Number ◽  
Boundary Layers ◽  
Turbulence Model ◽  
Turbulent Viscosity ◽  
Low Reynolds Number ◽  
Viscous Sublayer ◽  
Mean Velocity ◽  
Bottom Boundary ◽  
Bottom Boundary Layers ◽  
Low Reynolds

Characteristics of mean velocity and turbulence properties in oscillatory bottom boundary layers are investigated with low- Reynolds number turbulence model. Since this model is capable to describe the flow field close to the bottom, special attentions are paid on the characteristics of the viscous sublayer. Several interesting results, which coincide with or differ from existing knowledge on steady bottom boundary layers, are presented in paticular on the mean velocity profile, turbulent viscosity coefficient and growth of the viscous sublayer.

Research on improvements of low Reynolds number turbulence model based on flow around automobiles

2020 ◽  
Vol 78 (11) ◽  
pp. 674-695
Author(s):  
Yi Yang ◽  
Guanglin Qiang ◽  
Zhen Chen ◽  
Zhengqi Gu ◽  
Yong Zhang
Keyword(s):  
Reynolds Number ◽  
Turbulence Model ◽  
Low Reynolds Number ◽  
Model Based ◽  
Low Reynolds

Shear Layer Development, Separation, and Stability Over a Low-Reynolds Number Airfoil

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Paul Ziadé ◽  
Mark A. Feero ◽  
Philippe Lavoie ◽  
Pierre E. Sullivan
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Shear Layer ◽  
Separation Bubble ◽  
Low Reynolds Number ◽  
Base Flow ◽  
Mean Velocity ◽  
Laminar Separation ◽  
Low Reynolds ◽  
Layer Development

The shear layer development for a NACA 0025 airfoil at a low Reynolds number was investigated experimentally and numerically using large eddy simulation (LES). Two angles of attack (AOAs) were considered: 5 deg and 12 deg. Experiments and numerics confirm that two flow regimes are present. The first regime, present for an angle-of-attack of 5 deg, exhibits boundary layer reattachment with formation of a laminar separation bubble. The second regime consists of boundary layer separation without reattachment. Linear stability analysis (LSA) of mean velocity profiles is shown to provide adequate agreement between measured and computed growth rates. The stability equations exhibit significant sensitivity to variations in the base flow. This highlights that caution must be applied when experimental or computational uncertainties are present, particularly when performing comparisons. LSA suggests that the first regime is characterized by high frequency instabilities with low spatial growth, whereas the second regime experiences low frequency instabilities with more rapid growth. Spectral analysis confirms the dominance of a central frequency in the laminar separation region of the shear layer, and the importance of nonlinear interactions with harmonics in the transition process.

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