<abstract xmlns="http://www.w3.org/1999/xhtml">Shear stress is one of the most critical parameters in hydraulic and coastal engineering, which is often measured indirectly. Since there is no instrument to measure this parameter directly and given that it is usually calculated by measuring other parameters such as velocity and pressure and using some equations, shear stress measurement is often accompanied with large measurement errors. In this study, a new technique and direct measurement using physical modeling in a hydraulic knife-edge flume and load cell were employed to measure the shear stress in a rectangular channel with rigid unsubmerged vegetation with Dv= 20, 25, and 32mm inQ=25 and 30 Lit/S and y=10, 12, 17, and 20 cm. The results indicate that the shear stress and the dimensionless <inline-formula><alternatives><inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/j_jaes-2019-0021_eq_001.png"></inline-graphic><math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mrow><mfrac><mrow><msub><mrow><mi>τ</mi></mrow><mn>0</mn></msub></mrow><mi>τ</mi></mfrac></mrow></math><tex-math>{{{\tau _0}} \over \tau }</tex-math></alternatives></inline-formula> ratio decrease in a constant flow discharge with increasing the flow depth. It was also shown that the shear stress would be enhanced with an increasein vegetation diameter due to increasing vegetation density against flow. According to dimensionless ratios of <inline-formula><alternatives><inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/j_jaes-2019-0021_eq_002.png"></inline-graphic><math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mrow><mfrac><mrow><msub><mrow><mi>τ</mi></mrow><mn>0</mn></msub></mrow><mi>τ</mi></mfrac></mrow></math><tex-math>{{{\tau _0}} \over \tau }</tex-math></alternatives></inline-formula> and <inline-formula><alternatives><inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/j_jaes-2019-0021_eq_003.png"></inline-graphic><math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mrow><mfrac><mrow><msub><mrow><mi>D</mi></mrow><mi>v</mi></msub></mrow><mi>y</mi></mfrac></mrow></math><tex-math>{{{D_v}} \over y}</tex-math></alternatives></inline-formula> in the graphs and considering the trend lines with appropriate correlation coefficients, some equations were presented to calculate the shear stress in the concerned range.</abstract>

Shear stress is one of the most critical parameters in hydraulic and coastal engineering, which is often measured indirectly. Since there is no instrument to measure this parameter directly and given that it is usually calculated by measuring other parameters such as velocity and pressure and using some equations, shear stress measurement is often accompanied with large measurement errors. In this study, a new technique and direct measurement using physical modeling in a hydraulic knife-edge flume and load cell were employed to measure the shear stress in a rectangular channel with rigid unsubmerged vegetation with Dv= 20, 25, and 32mm inQ=25 and 30 Lit/S and y=10, 12, 17, and 20 cm. The results indicate that the shear stress and the dimensionless τ0τ{{{\tau _0}} \over \tau } ratio decrease in a constant flow discharge with increasing the flow depth. It was also shown that the shear stress would be enhanced with an increasein vegetation diameter due to increasing vegetation density against flow. According to dimensionless ratios of τ0τ{{{\tau _0}} \over \tau } and Dvy{{{D_v}} \over y} in the graphs and considering the trend lines with appropriate correlation coefficients, some equations were presented to calculate the shear stress in the concerned range.

Experimental Study of the Effects of Flow Discharge, Diameter, and Depth on Shear Stress in a Rectangular Channel with Rigid Unsubmerged Vegetation

Department of Offshore Structures, Faculty of Marine Engineering

Khorramshahr University of Marine Science and Technology

Journal of Applied Engineering Sciences

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Shear stress is one of the most critical parameters in hydraulic and coastal engineering, which is often measured indirectly. Since there is no instrument to...

Experimental Study of the Effects of Flow Discharge, Diameter, and Depth on Shear Stress in a Rectangular Channel with Rigid Unsubmerged Vegetation

Published Online: Dec 21, 2019

Page range: 155 - 160

Received: Dec 15, 2018

Accepted: Feb 16, 2019

DOI: https://doi.org/10.2478/jaes-2019-0021

Keywords
Vegetation, Rectangular channel, Shear stress, Physical model, Knife edge flume, Load cell

© 2019 Maturi Foad et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Experimental Study of the Effects of Flow Discharge, Diameter, and Depth on Shear Stress in a Rectangular Channel with Rigid Unsubmerged Vegetation

Published Online: Dec 21, 2019

Page range: 155 - 160

Received: Dec 15, 2018

Accepted: Feb 16, 2019

DOI: https://doi.org/10.2478/jaes-2019-0021

KeywordsVegetation, Rectangular channel, Shear stress, Physical model, Knife edge flume, Load cell

© 2019 Maturi Foad et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Keywords
Vegetation, Rectangular channel, Shear stress, Physical model, Knife edge flume, Load cell