Investigation of Shear Stress Distribution in a 90 Degree Channel Bend

Lee, Seung Kyu; Dang, Thanhtrung; Le, Van Tuan

doi:10.2478/ijame-2019-0014

Cited by 4 publications

(5 citation statements)

References 13 publications

(10 reference statements)

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“…River bed shear stress is a crucial hydrodynamics parameter, which can potentially impact river bed evolution and therefore the fish habitat (Lee et al, 2019; Mirauda & Russo, 2020). The river bed shear stress can be calculated as:

τ_{b} goodbreak= \frac{1}{2} ρ C_{d} ((), u, v) \sqrt{u^{2} + v^{2}}

…”

Section: Methodsmentioning

confidence: 99%

Evaluating the physical habitat of riffle‐pool design in support of river habitat protection and rehabilitation

Wang,

Yang,

Bao

et al. 2023

Ecohydrology

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Riffle‐pool constructions are common practice in river management and fish conservation, but insufficient science exists to guide objective design of riffle‐pool. Understanding the spatial design of a riffle‐pool in river systems has significant value because it can provide important information to ameliorate aquatic species decline. In this study, six types of riffle‐pool structures were designed to assess hydrodynamic and riverbed morphology effects on stream habitat status. A two‐dimensional ecohydraulic model was used to assess the roles of different riffle‐pool designs in river habitat conditions. The natural flow condition and three types of flood flow conditions were applied to the six types of riffle‐pool structures to evaluate the habitat quality and the sustainability of the riffle‐pool design in mountain rivers. The long‐term impacts of the hydrodynamic and hydromorphology conditions on river physical habitat status were also analysed. The results indicate substantial differences in habitat quality among six riffle‐pool structures. It was found that narrow riffle‐pool construction yielded the best performance for the fish habitat, which had the best habitat quality among six riffle‐pool designs with the smallest pool area. In the same riffle‐pool structure, the habitat suitability in the riffle‐pool sequence will primarily increase more rapidly and then decrease gradually along with the discharge increase. Under the flood discharge scenarios, low flood discharge could improve riffle‐pool habitat quality, while high flood discharge could fragment the riffle‐pool habitat quality further. The long‐term hydrodynamic conditions have the same effects on all six cases. Overall, low discharge and smaller pool design would be beneficial to the river system, which could help maintain habitat diversity of mountain rivers. This analysis could provide valuable information for river management and decision‐making, which could assist in designing better mountain river habitats to promote conservation and rehabilitation of endangered biota.

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τ_{b} goodbreak= \frac{1}{2} ρ C_{d} ((), u, v) \sqrt{u^{2} + v^{2}}

…”

Section: Methodsmentioning

confidence: 99%

Evaluating the physical habitat of riffle‐pool design in support of river habitat protection and rehabilitation

Wang,

Yang,

Bao

et al. 2023

Ecohydrology

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“…The presented model simulated the behavior of measured flow in laboratory channels using latitudinal variations of the artificially made shear stress [4]. Lee et al (2019) concluded that the maximum shear stress occurred at the beginning of the bend near the inner wall and at the end of the bend near the outer wall, for a radius of curvature of less than three [5]. The results indicated that the erosion of the outer wall in low flow conditions, with a Froude number of 0.35, began upstream from the top of the bend.…”

Section: Introductionmentioning

confidence: 99%

Flow Pattern and Erosion in a 90-Degrees Sharp Bend around a W−Weir

Atashi

Bejestan

Lim

2022

Water

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Different flow-altering methods, such as W−Weirs, have been developed to reduce erosion. For this study, we performed two experiments: (1) installing a W−Weir in various positions to determine the best angle for placement, and (2) investigating the variation of flow patterns and bed shear stress distribution in a 90-degree sharp bend by measuring the 3D components of flow velocities, with and without W−Weirs, where the greatest scour depth occurs. The results from the three installation angles indicate that less scour depth and volume of sediment removal occur when the weir is located close to the end of a bend. In addition, the value of the secondary circular power without a weir was higher than the position with a weir; however, this value significantly increased at 70 degrees due to turbulence flow near the W−Weir. This secondary flow power reduction at 45 degrees with a W−Weir increased by 65.8 percent for a Froude number value of 0.17, and by 29.8 percent for a Froude number value of 0.28, compared to values without the W−Weir, respectively.

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“…Figura 4 Fórmulas que describen el esfuerzo cortante según el método de la profundidad promedio (Lee, Dang, & Le, 2019) La información obtenida a través de los sensores en el canal y usando el método de la profundidad promedio muestran que para un canal curvo de 90°, el máximo esfuerzo se ubica en los 70° de la sección teniendo valores 3.5 mayores al mínimo y decrece hasta el tramo final de canal, tal como se muestra en la siguiente figura (Lee, Dang, & Le, 2019).…”

Section: Estado Del Arteunclassified

“…Figura 5 Ubicación del esfuerzo cortante máximo (línea roja) a través del canal curvo. (Lee, Dang, & Le, 2019) Frente al problema de erosión ya descrito, la investigación "River Management with Submerged Vanes" sugiere el uso de estructuras que permiten modificar el patrón de flujo cercano a la ribera y redistribuirlo, junto el transporte de sedimentos, a lo largo de la sección del rio. Este método fue descrito por Odgaard y Wang (1993), tienen un ángulo de ataque entre 10° y 20° en el sentido del flujo y una altura inicial del 10 al 40% del tirante de diseño.…”

Section: Estado Del Arteunclassified

“…Adaptado del artículo «The movement of the regularly rive meanders on constant discharge», por Terrence et al, 2002. .................... 6 Figura Fórmulas que describen el esfuerzo cortante según el método de la profundidad promedio (Lee, Dang, & Le, 2019) Figura 6 Socavación en pilares de puentes ubicados en las curvas de ríos, donde existe pérdida de sedimentos (Zarei, Vaghefi, & Hashemi, 2019) Figura Reducción de socavación debido al uso de submerged vanes (Zarei, Vaghefi, & Hashemi, 2019)…”

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Control de erosión fluvial en la curva externa, haciendo uso de paletas sumergidas en los sectores La Perla-Florida y Cantagallo en el Rio Rímac aplicando modelamiento numérico

Ravines¹,

Vargas²

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La presente tesis tiene como objetivo evaluar una propuesta para el control de erosión fluvial de la curva externa del rio Rimác ubicada entre los sectores Cantagallo y La Perla en Chosica, verificando su eficacia a través de un modelamiento con fines de calcular la socavación producida para diferentes periodos de retorno y proponer como estructura de control a las paletas sumergidas, comparando ambos resultados obtenidos para evaluar sus beneficios. El tramo escogido presentó fallas en los muros de contención ubicados a lo largo del cauce según un estudio previo realizado por el INGEMMET, por lo que es necesario mejorar la infraestructura ya construida, por lo que la presencia de las paletas sumergidas podría actuar como tal. Por este motivo, el modelamiento hidráulico, realizado en el software Iber, nos permitirá conocer el comportamiento del río para obtener las variables de diseño y conocer los valores de velocidades y esfuerzos cortantes de fondo producidos en la curva externa. Se realizó la simulación para dos escenarios, uno considerando las máximas avenidas producidas en años previos y el segundo despreciando dichos valores. Esto nos permite comparar las dimensiones y comportamiento de ambas estructuras para un futuro diseño. Finalmente, en ambos escenarios se verificó que la presencia de las paletas sumergidas en la curva externa reduce los niveles de erosión local y general producido para los diferentes caudales simulados, por lo que resulta una estructura viable a ser aplicada como medida de control.

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Investigation of Shear Stress Distribution in a 90 Degree Channel Bend

Cited by 4 publications

References 13 publications

Evaluating the physical habitat of riffle‐pool design in support of river habitat protection and rehabilitation

Evaluating the physical habitat of riffle‐pool design in support of river habitat protection and rehabilitation

Flow Pattern and Erosion in a 90-Degrees Sharp Bend around a W−Weir

Control de erosión fluvial en la curva externa, haciendo uso de paletas sumergidas en los sectores La Perla-Florida y Cantagallo en el Rio Rímac aplicando modelamiento numérico

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