Modeling Depth-Averaged Velocity and Boundary Shear in Trapezoidal Channels with Secondary Flows

Knight, Donald W.; Omran, Mazen; Tang, Xiaonan

doi:10.1061/(asce)0733-9429(2007)133:1(39)

Cited by 92 publications

(59 citation statements)

References 13 publications

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“…Knight et al [17] suggested that more accurate results can be obtained by using more divided panels in lateral distribution methods (LDM), because of the complex secondary flow distribution in the single channel. In this paper, the proposed model is also a two-dimensional LDM method (outlined in Section 4) applied in a meandering compound channel and therefore, each of the seven test sections (CS1 to CS7) is d ivided into several panels to obtain accurate lateral depth-averaged velocity distributions along a meander.…”

Section: Region Divided Theorymentioning

confidence: 99%

An analytical model for lateral depth-averaged velocity distributions along a meander in curved compound channels

Wright

Liu

Yang

2014

Advances in Water Resources

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Section: Region Divided Theorymentioning

confidence: 99%

An analytical model for lateral depth-averaged velocity distributions along a meander in curved compound channels

Wright

Liu

Yang

2014

Advances in Water Resources

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“…In order to demonstrate the advantages of the proposed approach over previous calibration attempts, a comparison was made with two examples taken from Knight et al (2007). Figure 13 shows the depth-averaged velocity and boundary shear stress distributions for two smooth homogeneous test cases along with the calculated values of the four objective functions (Equations (13) - (16) …”

Section: Preliminary Parameter Guidelinesmentioning

confidence: 99%

A novel application of a multi-objective evolutionary algorithm in open channel flow modelling

Sharifi

Sterling

Knight

2009

Journal of Hydroinformatics

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The Shiono and Knight method (SKM) is a simple depth-averaged flow model, based on the RANS equations which can be used to estimate the lateral distributions of depth-averaged velocity and boundary shear stress for flows in straight prismatic channels with the minimum of computational effort. However, in order to apply the SKM, detailed knowledge relating to the lateral variation of the friction factor ( f ), dimensionless eddy viscosity (l) and a sink term representing the effects of secondary flow (G) are required. In this paper a multi-objective evolutionary algorithm is used to study the lateral variation and value of these parameters for simple trapezoidal channels over a wide range of aspect ratios through the model calibration process. Based on the available experimental data, four objectives are selected and the NSGA-II algorithm is applied to several datasets. The best answer for each set is then selected based on a proposed methodology. Rules relating f, l and G to the wetted parameter ratio (P b /P w ) for a variety of situations have been developed which provide practical guidance for the engineer on choosing the appropriate parameters in the SKM model.

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“…Abril and Knight (2004) and Knight et al (2007) demonstrated that the λ value has no significant influence on the SKM prediction. Therefore, in this study, a constant value λ mc = 0.07 proposed by Knight et al (2004) was used in the main channel panel.…”

Section: Calibration For Skm Modelmentioning

confidence: 99%

“…They also showed that the secondary flow term may be assumed to be proportional to the gravitational term and suggested the secondary flow coefficient (k) as a proportionality constant. Knight et al (2007) analysed the modelling of the boundary shear in trapezoidal channels through investigating the effect of secondary flows on the boundary shear. Liao and Knight (2007) suggested a simple procedure for determining the analytic stage-discharge relationship, involving all three key parameters in SKM model, f, λ, and Г.…”

Section: Introductionmentioning

confidence: 99%

Application of the Shiono and Knight Method in asymmetric compound channels with different side slopes of the internal wall

2018

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The Shiono and Knight Method (SKM) is widely used to predict the lateral distribution of depth-averaged velocity and boundary shear stress for flows in compound channels. Three calibrating coefficients need to be estimated for applying the SKM, namely eddy viscosity coefficient (λ), friction factor (f) and secondary flow coefficient (k). There are several tested methods which can satisfactorily be used to estimate λ, f. However, the calibration of secondary flow coefficients k to account for secondary flow effects correctly is still problematic. In this paper, the calibration of secondary flow coefficients is established by employing two approaches to estimate correct values of k for simulating asymmetric compound channel with different side slopes of the internal wall. The first approach is based on Abril and Knight (2004) who suggest fixed values for main channel and floodplain regions. In the second approach, the equations developed by Devi and Khatua (2017) that relate the variation of the secondary flow coefficients with the relative depth (β) and width ratio (α) are used. The results indicate that the calibration method developed by Devi and Khatua (2017) is a better choice for calibrating the secondary flow coefficients than using the first approach which assumes a fixed value of k for different flow depths. The results also indicate that the boundary condition based on the shear force continuity can successfully be used for simulating rectangular compound channels, while the continuity of depth-averaged velocity and its gradient is accepted boundary condition in simulations of trapezoidal compound channels. However, the SKM performance for predicting the boundary shear stress over the shear layer region may not be improved by only imposing the suitable calibrated values of secondary flow coefficients. This is because difficulties of modelling the complex interaction that develops between the flows in the main channel and on the floodplain in this region.

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Modeling Depth-Averaged Velocity and Boundary Shear in Trapezoidal Channels with Secondary Flows

Cited by 92 publications

References 13 publications

An analytical model for lateral depth-averaged velocity distributions along a meander in curved compound channels

An analytical model for lateral depth-averaged velocity distributions along a meander in curved compound channels

A novel application of a multi-objective evolutionary algorithm in open channel flow modelling

Application of the Shiono and Knight Method in asymmetric compound channels with different side slopes of the internal wall

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