scholarly journals An Enhanced Treatment of Boundary Conditions for 2D RANS Streamwise Velocity Models in Open Channel Flow

Water ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1001
Author(s):  
Juan Alfonso Figuérez ◽  
Álvaro Galán ◽  
Javier González
Keyword(s):  
Shear Stress ◽  
Free Surface ◽  
Boundary Conditions ◽  
Streamwise Velocity ◽  
Surface Boundary ◽  
Surface Shear Stress ◽  
Law Of The Wall ◽  
Velocity Models ◽  
Boundary Shear ◽  
Boundary Shear Stress

A 2D streamwise velocity model based on the Reynolds Averaged Navier–Stokes (RANS) is a useful approach to predict the boundary shear stress and the streamwise velocity in a free surface stream where secondary flows are not relevant. Boundary conditions treatment is a key aspect implementing these models. A low computational cost and fully predictive numerical model with a novel treatment of boundary conditions is presented. The main features of the modified model are the employment of a modified law of the wall valid for any roughness condition, the estimation of the boundary shear stress is done only focusing on the near-contour region, the use of a full-predictive physical based model for the eddy viscosity distribution and the incorporation of the free surface shear stress due to water–air interface. The validation of the proposed changes was performed with a substantial number of experimental cases available in the literature using different cross-section shapes (circular, rectangular, trapezoidal and compound section) and roughness condition with quite good agreement. Preliminary results suggest that the influence of the free surface boundary layer has a significant impact on the results for both the streamwise velocity and boundary shear stress in windy conditions. The proposed approach allows its considerations in practical applications.

Boundary Shear Stress in Turbulent Boundary Layers on Smooth Boundaries

1967 ◽  
Vol 71 (673) ◽  
pp. 52-53 ◽  
Author(s):  
Dr. N. Rajaratnam ◽  
C. R. Froelich
Keyword(s):  
Shear Stress ◽  
Turbulent Flow ◽  
Mass Density ◽  
Flow Region ◽  
Viscous Sublayer ◽  
Mean Velocity ◽  
Law Of The Wall ◽  
Boundary Shear ◽  
Image Position ◽  
Boundary Shear Stress

It is well known that in the case of turbulent flow over smooth boundaries, the velocity distribution in the neigh- i bourhood of the wall is given by the law of the wall, c written aswhereuis the turbulent mean velocity at a normal distance of y from the boundary,u*is the shear velocity equal tobeing the boundary shear stress andρthe mass density of the fluid andvis the coefficient of kinematic viscosity. In the viscous sublayer, eqn. (1) becomesand in the turbulent flow region above the sublayer and the transition region, foryu*/v> 30, eqn. (1) becomeswhereAandBare coefficients.

Modeling streamwise velocity and boundary shear stress of vegetation-covered flow

2018 ◽  
Vol 92 ◽  
pp. 379-387 ◽  
Author(s):  
Lijuan Han ◽  
Yuhong Zeng ◽  
Li Chen ◽  
Ming Li
Keyword(s):  
Shear Stress ◽  
Streamwise Velocity ◽  
Boundary Shear ◽  
Boundary Shear Stress

scholarly journals Boundary Shear Stress Analysis in Meandering Channels at the Bend Apex

2015 ◽  
Vol 4 ◽  
pp. 812-818 ◽  
Author(s):  
Sovan Sankalp ◽  
Kishanjit. K. Khatua ◽  
Arpan Pradhan
Keyword(s):  
Shear Stress ◽  
Stress Analysis ◽  
Meandering Channels ◽  
Boundary Shear ◽  
Boundary Shear Stress

FLOOD HYDRAULICS DUE TO EMERGENT VEGETATION ALONG A RIPARIAN ZONE IN MEANDERING CHANNELS

2016 ◽  
Vol 78 (9-4) ◽  
Author(s):  
Zulkiflee Ibrahim ◽  
Zulhilmi Ismail ◽  
Sobri Harun ◽  
Koji Shiono ◽  
Nazirah Mohd. Zuki ◽  
...  
Keyword(s):  
Shear Stress ◽  
Flow Resistance ◽  
Riparian Zone ◽  
Streamwise Vorticity ◽  
Floodplain Vegetation ◽  
Meandering Channel ◽  
Meandering Channels ◽  
Boundary Shear ◽  
Residential Properties ◽  
Boundary Shear Stress

Frequent floods around the globe including recent events in several states in Malaysia have damaged the residential properties, infrastructures and crops or even deaths. Clearing vegetations or trees on the floodplain has been pointed out as a contributing factor to the damages. Thus, the influence of floodplain vegetation on the river hydraulics during flooding must be better understood. The hydraulics of flood flows in non-erodible vegetated meandering channel was experimented in the laboratory where two-lined steel rods were installed along a riparian zone to simulate as trees. The stage-discharge relationship, flow resistance, depth-averaged velocity, streamwise vorticity and boundary shear stress patterns during shallow and deep flood inundations were studied. The findings showed that floodplain vegetation had increased the channel flow depth by 32% and its flow resistance. The velocity in vegetated zone was lowered and the shear stress reduced by 86.5% to 91% along the river meander. In addition, the trees also limit flow interaction between main channel and floodplain

Modelling boundary shear stress in highly sinuous meandering channels

2013 ◽  
Vol 20 (2) ◽  
pp. 161-168 ◽  
Author(s):  
M. Patnaik ◽  
K.C. Patra ◽  
K.K. Khatua ◽  
L. Mohanty
Keyword(s):  
Shear Stress ◽  
Meandering Channels ◽  
Boundary Shear ◽  
Boundary Shear Stress

scholarly journals Modeling effects of bank friction and woody bank vegetation on channel flow and boundary shear stress in the Rio Puerco, New Mexico

2005 ◽  
Vol 110 (F4) ◽  
pp. n/a-n/a ◽  
Author(s):  
E. R. Griffin ◽  
J. W. Kean ◽  
K. R. Vincent ◽  
J. D. Smith ◽  
J. M. Friedman
Keyword(s):  
Shear Stress ◽  
New Mexico ◽  
Channel Flow ◽  
Boundary Shear ◽  
Boundary Shear Stress
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