Boundary Shear in Smooth Rectangular Ducts

Knight, Donald W.; Patel, H.

doi:10.1061/(asce)0733-9429(1985)111:1(29)

Cited by 83 publications

(56 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These comparisons showed that the MBM is comparable with these existing methods. When the estimated shear stress by MBM was compared with Lawrence (1960), Knight and Patel (1985) and Leutheusser (1963), it presents this method works well and agrees with these existing data. No empirical coefficient or assumption is involved in the method.…”

Section: Discussionsupporting

confidence: 73%

“…8 and Fig. 9 shows the comparison between the boundary shear stress obtained by MBM and other researchers' measured results, including Lawrence [19], Leutheusser [20] and Knight and Patel [1]. It is seen that the relative bed shear stress…”

Section: Mbm Application To Smooth Closed Duct Flowsmentioning

confidence: 66%

“…It is generally accepted that there are many similarities between flow in a rectangular open channel and closed duct [1][2]. Knowledge of the distribution of boundary shear stress around the wetted perimeter of an open channel or closed duct is a matter of fundamental importance in many hydraulic equations concerning resistance, sediment, dispersion, or cavitations' problems [3][4].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Application of Main Flow Data in the Determination of Boundary Shear Stress in Smooth Closed Ducts

Han

Yang

Dharmasiri

2012

World Environmental and Water Resources Congress 2012

View full text Add to dashboard Cite

Boundary shear stress plays an important role in momentum and mass transfers, but it is very difficult to determine experimentally. This paper develops a new method which can evaluate the boundary shear stress using the main flow data based on Momentum Balance Method (MBM). A theoretical relationship between the boundary shear stress and parameters of main flow region is established. The obtained results from MBM agree well with other methods, indicating that the new method is reasonable and reliable. The significant contribution of MBM is that the local boundary shear stress accurately and quickly can be determined by application of this new method . Hence, MBM may provide a useful tool for hydraulic engineers who need a simple and easy way to measure the boundary shear stress.

show abstract

Section: Discussionsupporting

confidence: 73%

Section: Mbm Application To Smooth Closed Duct Flowsmentioning

confidence: 66%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Application of Main Flow Data in the Determination of Boundary Shear Stress in Smooth Closed Ducts

Han

Yang

Dharmasiri

2012

World Environmental and Water Resources Congress 2012

View full text Add to dashboard Cite

show abstract

“…Knight and Patel (1985) calculated boundary shear stress distributions in fully developed turbulent flows in smooth rectangular ducts and extracted the following equation:…”

Section: Data Description Usedmentioning

confidence: 99%

“…The presented equation for a trapezoidal channel could not predict acceptable values for wall shear stress, and with RMSE of 0.1826, it exhibited low precision for predicting wall shear stress. The equations proposed for smooth ducts presented by Knight and Patel (1985) and Rhodes and Knight (1994) had the highest error values (RMSE of 0.2694 and 0.2554, respectively) and indicated the equations' poor accuracy in predicting wall shear stress.…”

Section: Comparison Between the Best Model And Other Equationsmentioning

confidence: 99%

Using two soft computing methods to predict wall and bed shear stress in smooth rectangular channels

2017

View full text Add to dashboard Cite

Two soft computing methods were extended in order to predict the mean wall and bed shear stress in open channels. The genetic programming (GP) and Genetic Algorithm Artificial Neural Network (GAA) were investigated to determine the accuracy of these models in estimating wall and bed shear stress. The GP and GAA model results were compared in terms of testing dataset in order to find the best model. In modeling both bed and wall shear stress, the GP model performed better with RMSE of 0.0264 and 0.0185, respectively. Then both proposed models were compared with equations for rectangular open channels, trapezoidal channels and ducts. According to the results, the proposed models performed the best in predicting wall and bed shear stress in smooth rectangular channels. The obtained equation for rectangular channels could estimate values closer to experimental data, but the equations for ducts had poor, inaccurate results in predicting wall and bed shear stress. The equation presented for trapezoidal channels did not have acceptable accuracy in predicting wall and bed shear stress either.

show abstract

Estimating bed shear stress from remotely measured surface turbulent dissipation fields in open channel flows

Johnson

Cowen

2017

Water Resources Research

View full text Add to dashboard Cite

Synoptic information on bed shear stress is necessary in predicting the transport of sediments and environmental contaminants in rivers and open channels. Existing methods of estimating bed shear stress typically involve measuring vertical profiles of streamwise velocity or Reynolds stress and taking advantage of the logarithmic or the constant stress region, respectively, to determine friction velocity and subsequently, bed shear stress. While effective, these methods yield local measurements of bed shear stress only. Direct measurements of bed shear stress can also be obtained through measurements with a drag plate. However, this method yields average shear stress information over the area of the plate and is impractical for large‐scale implementation in the field. Here we present a method capable of providing continuous synoptic measurements of bed shear stress over a large field‐of‐view. A series of Large‐Scale Particle Image Velocimetry (LSPIV) and Acoustic Doppler Velocimetry (ADV) measurements were made in a variety of flows generated in a wide‐open channel facility. Turbulent dissipation is calculated on the free surface from the 2‐D LSPIV results and is correlated with near‐surface ADV measurements of turbulent dissipation in the water column. The ADV results are consistent with the Nezu (1977) established relationship for the vertical variation of turbulent dissipation in the water column. Knowledge of the correlation between free‐surface and near‐surface dissipation values coupled with Nezu's (1977) relationship allow a robust and accurate estimate of friction velocity to be made and subsequently, shear stress at the bed can be estimated.

show abstract

Boundary Shear in Smooth Rectangular Ducts

Cited by 83 publications

References 13 publications

Application of Main Flow Data in the Determination of Boundary Shear Stress in Smooth Closed Ducts

Application of Main Flow Data in the Determination of Boundary Shear Stress in Smooth Closed Ducts

Using two soft computing methods to predict wall and bed shear stress in smooth rectangular channels

Estimating bed shear stress from remotely measured surface turbulent dissipation fields in open channel flows

Contact Info

Product

Resources

About