Flow and erosion at a bend in the braided Jamuna River

Uddin, Mohammad Nazim; Rahman, Md. Munsur

doi:10.1016/s1001-6279(13)60008-6

Cited by 25 publications

(13 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Many researchers from the past so far have been trying to study the structure of the flow around the bridge piers with numerical and experimental methods. These include Dey and Raikar (2007), Kirkil et al (2008), Rodriguez and Garcia (2008), Belcher and Fox (2009), Beheshti and Ataie-Ashtiani (2010), Kirkil and Constantinescu (2010), Şarlak and Tiğrek (2011), Kumar et al (2012), Ataie-Ashtiani and Aslani-Kordkandi (2012, 2013, Das et al (2013aDas et al ( , 2013b, Das and Mazumdar (2015), Ma et al (2015), Beheshti and Ataie-Ashtiani (2016), , Ma et al (2016), Karimi et al (2017), Khan et al (2017) in the straight path and also Naji Abhari et al (2010), Barbhuiya and Talukdar (2010), Constantinescu et al (2011), Uddin and Rahman (2012), Tang and Knight (2014), Vaghefi et al (2015), Vaghefi et al (2016), Ben Mohammad Khajeh et al (2017, Dey et al (2017), Vaghefi et al (2017), Abdi Chooplou et al (2018), Gholami et al (2019) in the bend. Considering that previous studies have shown that there was no comprehensive study on flow pattern around the bridge pier with collar in the case of placement in bend, it is important to understand the pattern of the flow around the bridge pier protected by collar.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation on the Effect of Increasing the Collar Thickness on the Flow Pattern around the Oblong Pier in 180˚ Sharp Bend with Balanced Bed

moghanloo¹,

Vaghefi

Ghodsian

2020

JAFM

View full text Add to dashboard Cite

In this paper, the effect of increase collar thickness has been investigated by considering other parameters affecting the flow pattern around the oblong bridge pier located at 90˚ from the 180˚ bend constant. Data acquisition was performed using the Vectrino 3D velocimeter. The leveling of the collar in both tests is constant and 0.4 times the pier diameter above the initial bed surface. The flow conditions were close to the motion threshold and bed balanced. The results showed that with an increase in the thickness of the collar by a factor of 4, the barrier surface is located in the flow path and the flow is deviated to the bed by colliding with the edge of the collar. This flow deviation that was due to the increase the collar thickness, led to 30% increase in the maximum depth of the scour hole upstream of the pier. Also, with the increase in the thickness of the collar, the tendency of the streamlines upstream of the pier to the inner bank increased, resulting in a 20% increase in the maximum sedimentation near the inner bank. The maximum turbulent kinetic energy at 80 degrees of the bend, corresponds with a protected pier with 3 mm thickness, equal to 620 cm 2 /s 2 .gr, which is reduced by 60% with increasing collar thickness.

show abstract

Section: Introductionmentioning

confidence: 99%

Experimental Investigation on the Effect of Increasing the Collar Thickness on the Flow Pattern around the Oblong Pier in 180˚ Sharp Bend with Balanced Bed

moghanloo¹,

Vaghefi

Ghodsian

2020

JAFM

View full text Add to dashboard Cite

show abstract

“…which have a very high social impact (Hasan & Kabir, 2014;Hasan & Islam, 2010). Natural disasters due to the hydrological process (i.e., erosion, flood) can directly affect human activities (Uddin & Rahman, 2012) which have a broader impact on economic and social context as well (Ferdous et al, 2019;Mutton & Haque, 2004). These types of rivers are sensitive to changes in their flood regime or sediment influx and can completely modify their geometry over a few decades (Rahman et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Impacts of Dredging on Fluvial Geomorphology in the Jamuna River, Bangladesh

Rahman¹,

Hasan²,

Eusufzai³

et al. 2021

GEP

View full text Add to dashboard Cite

Jamuna, a major braided river in Bangladesh, has an enormous hydrological impact on the surrounding areas and streams. Erosion and sedimentation in the Jamuna river cause a large flow fluctuation and floods round the year. Bangladesh Water Development Board has initiated a pilot capital dredging project in the Jamuna river in 2011-2012, aiming to guide the flow to reduce the risk of failure of the city area and right guide bundh of the Jamuna Bridge. This study explores the long-term role of dredging on river morphology using erosion-sedimentation numerical modeling approaches. Primary data were employed in numerical models to estimate the erosion-sedimentation and compared outputs with the real-time cross-sectional variation at selected sections along the reach during 2012-2013. The analysis suggested that the rate of sedimentation is higher (60% to 80%), where the dredging alignment crosses through the existing sandbar/char. Moreover, a cross-section comparison revealed that the channel near Sirajganj Hardpoint shifted towards the left (east) bank, and the channel within the study area developed very fast along the right (west) bank. However, satellite image analysis revealed that the major bankline shifting occurred from 2000 to 2010 and the channel shifting was observed from 2014 to 2018 along the reach, mostly, after the construction of some river training works. The variation of the channel persistence (40% -100%) selected part of the study area in the channel incidence map, indicating the rapid dynamic behavior of the river morphology. This study showed a promise that numerical approaches can predict the long-term hydrodynamic behavior of a braided river.

show abstract

“…They observed that, generally, in mild bends with any type of bed material, maximum velocity for the first half of the entrance zone of the bend is oriented toward the inner wall, and as it moves toward the end of the bend, gradually, its geometric location falls on the outer wall. Uddin and Rahman (2012) Blanckaert and Graf (2001) evaluated the three-dimensional velocity pattern and the cause of secondary and spiral flow formation in the bends experimentally. In relation to the numerical works, De Marchis and Napoli (2006) examined the flow pattern in sharp bends using computational fluid dynamic (CFD) as three dimensions.…”

Section: Introductionmentioning

confidence: 99%

An efficient classified radial basis neural network for prediction of flow variables in sharp open-channel bends

et al. 2019

View full text Add to dashboard Cite

In this study, a comparative analysis is done to evaluate the ability of classified radial basis function neural network (CRB-FNN) model in estimation of flow variables in sharp open-channel bends with bend angles of 60° and 90°. Accordingly, a RBFNN model is integrated with classification method to design a novel CRBFNN model to predict two velocity and flow depth parameters in a 60° sharp bend. Furthermore, Gholami et al. (Neural Comput Appl 30:1-15, 2018a) pointed out to acceptable ability and more efficiency improvement of hybrid CRBFNN model in prediction of flow variables in 90° sharp open-channel bend compared to simple RBF model. On the other hand, the flow pattern in sharp bends is more complicated than in mild open-channel bends. Moreover, the behavior of flow and its variables is varied in 60° and 90° sharp bends. Therefore, the present paper is aimed to evaluate the performance of RBF and CRBF models in two 60° and 90° (Gholami et al. 2018a) sharp open-channel bends. Available experimental data for velocity and flow depth at six different hydraulic conditions are used to train and test the CRBFNN and simple radial basis function neural network (RBFNN) networks in 60° open-channel bend. Accordingly, efficiency of both RBFNN and CRBFNN models in different bend cross sections is evaluated and compared with each other. The results show that using classified model has improved the simple RBF model performance, as in the CRBFNN model, the error root mean square error and mean absolute error value, 18% and 15.3% for the flow depth prediction and 9% and 5% for the velocity prediction compared to the simple RBFNN model is reduced, respectively. Furthermore, the comparison of model performance in 60° and 90° bends represents that both RBFNN and CRBFNN models in all discharge values in velocity prediction have more ability in 60° bend so that the mean absolute relative error (MARE) value in 60° bend is equal to 0.080 and 0.082 which are lower than MARE values in 90° bend (0.125 and 0.131 for RBFNN and CRBFNN, respectively). Furthermore, both RBFNN and CRBFNN models with lower MARE values equal to 0.015 and 0.012 in 90° bend have more accuracy than the models in 60° bend (0.017 and 0.014). Therefore, the proposed classified models can be used in design and implementation of the curved channels with various bend angles.

show abstract

Flow and erosion at a bend in the braided Jamuna River

Cited by 25 publications

References 10 publications

Experimental Investigation on the Effect of Increasing the Collar Thickness on the Flow Pattern around the Oblong Pier in 180˚ Sharp Bend with Balanced Bed

Experimental Investigation on the Effect of Increasing the Collar Thickness on the Flow Pattern around the Oblong Pier in 180˚ Sharp Bend with Balanced Bed

Impacts of Dredging on Fluvial Geomorphology in the Jamuna River, Bangladesh

An efficient classified radial basis neural network for prediction of flow variables in sharp open-channel bends

Contact Info

Product

Resources

About