Application of the Shiono and Knight Method in asymmetric compound channels with different side slopes of the internal wall
Abstract 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), frictio...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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SpringerOpen
2018-01-01
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| Series: | Applied Water Science |
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| Online Access: | http://link.springer.com/article/10.1007/s13201-018-0663-4 |
| _version_ | 1819056270996406272 |
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| author | Wisam Alawadi Wisam S. Al-Rekabi Ali H. Al-Aboodi |
| author_facet | Wisam Alawadi Wisam S. Al-Rekabi Ali H. Al-Aboodi |
| author_sort | Wisam Alawadi |
| collection | DOAJ |
| description | Abstract 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. |
| first_indexed | 2024-12-21T13:20:45Z |
| format | Article |
| id | doaj.art-cc5b02ef6e2145baa94eef8615378ecc |
| institution | Directory Open Access Journal |
| issn | 2190-5487 2190-5495 |
| language | English |
| last_indexed | 2024-12-21T13:20:45Z |
| publishDate | 2018-01-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | Applied Water Science |
| spelling | doaj.art-cc5b02ef6e2145baa94eef8615378ecc2022-12-21T19:02:36ZengSpringerOpenApplied Water Science2190-54872190-54952018-01-018111010.1007/s13201-018-0663-4Application of the Shiono and Knight Method in asymmetric compound channels with different side slopes of the internal wallWisam Alawadi0Wisam S. Al-Rekabi1Ali H. Al-Aboodi2School of Computing Science and Engineering, Newton Building, University of SalfordDepartment of Civil Engineering, College of Engineering, University of BasrahDepartment of Civil Engineering, College of Engineering, University of BasrahAbstract 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.http://link.springer.com/article/10.1007/s13201-018-0663-4Depth-averaged velocityBoundary shear stressSecondary flowsShiono and Knight MethodAsymmetric compound channels |
| spellingShingle | Wisam Alawadi Wisam S. Al-Rekabi Ali H. Al-Aboodi Application of the Shiono and Knight Method in asymmetric compound channels with different side slopes of the internal wall Applied Water Science Depth-averaged velocity Boundary shear stress Secondary flows Shiono and Knight Method Asymmetric compound channels |
| title | Application of the Shiono and Knight Method in asymmetric compound channels with different side slopes of the internal wall |
| title_full | Application of the Shiono and Knight Method in asymmetric compound channels with different side slopes of the internal wall |
| title_fullStr | Application of the Shiono and Knight Method in asymmetric compound channels with different side slopes of the internal wall |
| title_full_unstemmed | Application of the Shiono and Knight Method in asymmetric compound channels with different side slopes of the internal wall |
| title_short | Application of the Shiono and Knight Method in asymmetric compound channels with different side slopes of the internal wall |
| title_sort | application of the shiono and knight method in asymmetric compound channels with different side slopes of the internal wall |
| topic | Depth-averaged velocity Boundary shear stress Secondary flows Shiono and Knight Method Asymmetric compound channels |
| url | http://link.springer.com/article/10.1007/s13201-018-0663-4 |
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