Distribution of boundary shear in compound channel with rough floodplains

Patra, Kanhu Charan; Sahoo, N.; Khatua, Kishanjit Kumar

doi:10.2495/rbm130091

Cited by 5 publications

(5 citation statements)

References 22 publications

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“…Based on Equations ( 11)-( 13) and employing the empirical formula Equation ( 16), both sub-region discharges and boundary shear force of a compound cross-section can be calculated. Except for the experimental data shown in Table 1, other experimental data such as Bousmar [19] (Bousmar), Macintosh [20] (Macintosh, including two series RCC and TCC), Mohanty and Khatua [21] (M&K), Khatua et al [11] (Khatua), Al-Khatib et al [22] (Khatib), and Patra et al [23] (Patra) have been added into the discussion (Table 2). For symmetric-floodplain cases, there are 142 sets of data: the range of H is about 0.07~0.30 m; the range of B t is about 0.3~10 m; the Q range is about 0.0067~1.11 m 3 /s; the range of Froude number is about 0.30~2.30; µ 0 ranges from 1.05 to 20.52; α ranges from 0.0035 to 0.105.…”

Section: Comparisons Between Different Methodsmentioning

confidence: 99%

Study on the Coefficient of Apparent Shear Stress along Lines Dividing a Compound Cross-Section

Zhao,

Chen,

Qin

et al. 2024

Water

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A compound channel’s discharge capacity and boundary shear force can be predicted as a sum of the discharge capacity of different sub-regions once the apparent shear stress of the dividing line is reasonably quantified. The apparent shear stress was usually expressed as a coefficient multiplied by the difference between two squared velocities of two adjacent regions. This study investigated the range of the coefficient values and their influencing factors. Firstly, the optimal values of the coefficient were obtained based on experimental data. Then, comparisons between the optimal values and several parameters used in quantifying the apparent shear stress were conducted. The results show that the coefficient is mainly related to a morphological parameter of the floodplain and the ratio of resistance coefficients between the floodplain and the main channel. An empirical formula to calculate the coefficient was developed and introduced to calculate the flow discharge and boundary shear stress. Experimental data, including 142 sets of test data of symmetric-floodplain cases and 104 sets of one-floodplain cases, have been used to examine the prediction accuracy of discharges and boundary shear stress. For all these tests, the ranges of water depth of the main channel and the total width of the compound cross-section are about 0.05~0.30 m and 0.3~10 m, respectively; the Q range and the range of Froude numbers of the main channel flow are about 0.0033~1.11 m3/s and 0.3~2.3, respectively. Comparison with other methods and experimental data from both rigid and erodible compound channels indicated that the proposed method not only provided acceptable accuracy for the computation of discharge capacity and boundary shear stress of compound channels in labs but also gave insights for calculating discharge capacity in natural compound channels.

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Section: Comparisons Between Different Methodsmentioning

confidence: 99%

Study on the Coefficient of Apparent Shear Stress along Lines Dividing a Compound Cross-Section

Zhao,

Chen,

Qin

et al. 2024

Water

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“…Considering every state, the average value of information ( ) can be expressed as Equation (2). Function is defined using Shannon's [34] entropy as:…”

Section: Entropy Theorymentioning

confidence: 99%

“…Shear stress is used and applied in hydraulics, hydrology, fluid mechanics, and in various fields which is one of the most important mechanical factors [1]. It is a great challenge to the river engineers and researchers working in the field to estimate the distribution of bed shear stress in open channel flows [2].…”

Section: Introductionmentioning

confidence: 99%

Entropy-Based Shear Stress Distribution in Open Channel for all types of Flow using Experimental Data

Jeon

Kim

Choo

2021

Preprint

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Korea’s river design standards set general design standards for river and river-related projects in Korea, which systematize the technologies and methods involved in river-related projects. This includes measurement methods for parts necessary for river design, but do not include information on shear stress. Shear Stress is to one of the factors necessary for river design and operation. Shear stress is one of the most important hydraulic factors used in the fields of water especially for artificial channel design. Shear stress is calculated from the frictional force caused by viscosity and fluctuating fluid velocity. Current methods are based on past calculations, but factors such as boundary shear stress or energy gradient are difficult to actually measure or estimate. The point velocity throughout the entire cross section is needed to calculate the velocity gradient. In other words, the current Korea’s river design standards use tractive force, critical tractive force instead of shear stress because it is more difficult to calculate the shear stress in the current method. However, it is difficult to calculate the exact value due to the limitations of the formula to obtain the river factor called the tractive force. In addition, tractive force has limitations that use empirically identified base value for use in practice. This paper focuses on the modeling of shear stress distribution in open channel turbulent flow using entropy theory. In addition, this study suggests shear stress distribution formula, which can be easily used in practice after calculating the river-specific factor T. and that the part of the tractive force and critical tractive force in the Korea’s river design standards should be modified by the shear stress obtained by the proposed shear stress distribution method. The present study therefore focuses on the modeling of shear stress distribution in open channel turbulent flow using entropy theory. The shear stress distribution model is tested using a wide range of forty-two experimental runs collected from the literature. Then, an error analysis is performed to further evaluate the accuracy of the proposed model. The results revealed a correlation coefficient of approximately 0.95–0.99, indicating that the proposed method can estimate shear stress distribution accurately. Based on this, the results of the distribution of shear stress after calculating the river-specific factors show a correlation coefficient of about 0.86 to 0.98, which suggests that the equation can be applied in practice.

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“…Considering every state, the average value of information I(x) can be expressed as Equation (2). Function H(x) is defined using Shannon's [37] entropy as:…”

Section: Entropy Theorymentioning

confidence: 99%

“…Shear stress is used and applied in hydraulics, hydrology, fluid mechanics, and in various fields, and is one of the most important mechanical factors [1]. It is a great challenge to the river engineers and researchers working in the field to estimate the distribution of bed shear stress in open channel flows [2].…”

Section: Introductionmentioning

confidence: 99%

Entropy-Based Shear Stress Distribution in Open Channel for All Types of Flow Using Experimental Data

Choo

Jeon

Seo

2021

Entropy

View full text Add to dashboard Cite

Korean river design standards set general design standards for rivers and river-related projects in Korea, which systematize the technologies and methods involved in river-related projects. This includes measurement methods for parts necessary for river design, but does not include information on shear stress. Shear stress is one of the factors necessary for river design and operation. Shear stress is one of the most important hydraulic factors used in the fields of water, especially for artificial channel design. Shear stress is calculated from the frictional force caused by viscosity and fluctuating fluid velocity. Current methods are based on past calculations, but factors such as boundary shear stress or energy gradient are difficult to actually measure or estimate. The point velocity throughout the entire cross-section is needed to calculate the velocity gradient. In other words, the current Korean river design standards use tractive force and critical tractive force instead of shear stress because it is more difficult to calculate the shear stress in the current method. However, it is difficult to calculate the exact value due to the limitations of the formula to obtain the river factor called the tractive force. In addition, tractive force has limitations that use an empirically identified base value for use in practice. This paper focuses on the modeling of shear-stress distribution in open channel turbulent flow using entropy theory. In addition, this study suggests a shear stress distribution formula, which can easily be used in practice after calculating the river-specific factor T. The tractive force and critical tractive force in the Korean river design standards should be modified by the shear stress obtained by the proposed shear stress distribution method. The present study therefore focuses on the modeling of shear stress distribution in an open channel turbulent flow using entropy theory. The shear stress distribution model is tested using a wide range of forty-two experimental runs collected from the literature. Then, an error analysis is performed to further evaluate the accuracy of the proposed model. The results reveal a correlation coefficient of approximately 0.95–0.99, indicating that the proposed method can estimate shear-stress distribution accurately. Based on this, the results of the distribution of shear stress after calculating the river-specific factors show a correlation coefficient of about 0.86 to 0.98, which suggests that the equation can be applied in practice.

show abstract

Distribution of boundary shear in compound channel with rough floodplains

Cited by 5 publications

References 22 publications

Study on the Coefficient of Apparent Shear Stress along Lines Dividing a Compound Cross-Section

Study on the Coefficient of Apparent Shear Stress along Lines Dividing a Compound Cross-Section

Entropy-Based Shear Stress Distribution in Open Channel for all types of Flow using Experimental Data

Entropy-Based Shear Stress Distribution in Open Channel for All Types of Flow Using Experimental Data

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