scholarly journals Numerical Simulation of Local Scour around Three Cylindrical Piles in a Tandem Arrangement

Water ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 3623
Author(s):  
Jyh-Haw Tang ◽  
Aisyah Dwi Puspasari
Keyword(s):  
Numerical Simulation ◽  
Experimental Study ◽  
Numerical Model ◽  
Experimental Studies ◽  
Horseshoe Vortex ◽  
Local Scour ◽  
Scour Depth ◽  
Pile Groups ◽  
Tandem Arrangement ◽  
Flow Acceleration

Scouring is one of the most common potential causes of bridge pile foundation failure, with loss of life, economic and environmental impacts. Comprehensive studies on the numerical simulation of local scour around pile groups are still limited. This paper presents a numerical simulation using Flow-3D software to calculate the maximum sediment scour depth and investigate the mechanism around the groups of three cylinders in a tandem arrangement. A validation using the experimental study was carried out to confirm the reliability of the present numerical model. By using the Van Rijn transport rate equation and RNG k-ε turbulence model, the results of time evolution of scour depth and bed elevation contour show good agreement with the experimental study. The numerical simulation of three cylinders in a tandem arrangement were conducted with pile spacing ratios, G/D of 2 and 3. The local scour is affected by the horseshoe vortex from the downflow driven by the downward pressure gradient and rotates in front of the pile and the high bed shear stress, triggered by flow acceleration. The deepest maximum local scour depth is always obtained by the front pile as a shield pile, followed by the piles behind. The trend of the maximum local scour depth in a tandem arrangement is in accordance with the experimental studies and has a better agreement than previous numerical studies with the same model setup. This means that the numerical model used to simulate pile groups is accurate and capable of calculating the depth of sediment scour.

scholarly journals Effect of Inclination Angles on the Local Scour around a Submerged Cylinder

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2687
Author(s):  
Shaohua Wang ◽  
Shiyu Yang ◽  
Zhiguo He ◽  
Li Li ◽  
Yuezhang Xia
Keyword(s):  
Inclination Angle ◽  
Stokes Equations ◽  
Transport Model ◽  
Three Dimensional ◽  
Vertical Cylinder ◽  
Horseshoe Vortex ◽  
Local Scour ◽  
Scour Depth ◽  
Ocean Engineering ◽  
Bed Morphology

In ocean engineering and coastal environmental studies, local scour around a submerged structure is a typical issue, which is affected by the inclination of the structure. To investigate the effect of inclination directions and angles on flow structure and the bed morphology, a three-dimensional numerical model of a submerged inclined cylinder was established. In this model, the hydrodynamics are solved from the RANS (Reynolds-averaged Navier–Stokes) equations closed with the RNG k-ε turbulence model, while the bed morphology evolution is captured by the sediment transport model. In the case of vertical-cylinder scour, the simulation results agree well with existing laboratory experiments. In the cases of inclined-cylinder scour, the results show that the inclination direction not only changes the intensity and the location of the downflow but also modulates the pattern of the horseshoe vortex in front of the cylinder, thus influencing the local scour depth and the morphology of the bed. Compared with the case of vertical cylinder, the scour around an upstream-inclined cylinder is deeper, mainly due to the enhancement of downflow in front of the cylinder. The scour around a downstream-inclined cylinder is shallower and broader due to the weakened downflow and accelerated incoming flow. The maximum scour depth decreases with the inclination angle in the downstream-inclination case. In the upstream-inclination case, the maximum scour depth does not vary monotonously with the inclination angle, which results from a competitive effect of the horseshoe vortex and downflow in the front of the cylinder.

scholarly journals Improving the 2D Numerical Simulations on Local Scour Hole around Spur Dikes

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1462
Author(s):  
Chung-Ta Liao ◽  
Keh-Chia Yeh ◽  
Yin-Chi Lan ◽  
Ren-Kai Jhong ◽  
Yafei Jia
Keyword(s):  
Numerical Simulation ◽  
Three Dimensional ◽  
Local Scour ◽  
Bridge Piers ◽  
Scour Depth ◽  
Foundation Design ◽  
Mobile Bed ◽  
Scour Hole ◽  
Scour Holes ◽  
Spur Dikes

Local scour is a common threat to structures such as bridge piers, abutments, and dikes that are constructed on natural rivers. To reduce the risk of foundation failure, the understanding of local scour phenomenon around hydraulic structures is important. The well-predicted scour depth can be used as a reference for structural foundation design and river management. Numerical simulation is relatively efficient at studying these issues. Currently, two-dimensional (2D) mobile-bed models are widely used for river engineering. However, a common 2D model is inadequate for solving the three-dimensional (3D) flow field and local scour phenomenon because of the depth-averaged hypothesis. This causes the predicted scour depth to often be underestimated. In this study, a repose angle formula and bed geometry adjustment mechanism are integrated into a 2D mobile-bed model to improve the numerical simulation of local scour holes around structures. Comparison of the calculated and measured bed variation data reveals that a numerical model involving the improvement technique can predict the geometry of a local scour hole around spur dikes with reasonable accuracy and reliability.

scholarly journals Numerical Study of Local Scour around a Submarine Pipeline with a Spoiler Using a Symmetry Boundary Condition

Symmetry ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1847
Author(s):  
Chuan Zhou ◽  
Jianhua Li ◽  
Jun Wang ◽  
Guoqiang Tang
Keyword(s):  
Numerical Model ◽  
Stokes Equations ◽  
Numerical Study ◽  
Lift Coefficient ◽  
Numerical Results ◽  
Local Scour ◽  
Navier Stokes ◽  
Scour Depth ◽  
Submarine Pipeline ◽  
The Mean

A two-dimensional numerical model for solving the Navier–Stokes equations was developed to investigate the local scour around a submarine pipeline with a spoiler. Both the suspended load and the bed load were considered in the present numerical model. The focus of the present study is to investigate the effects of the spoiler length on the hydrodynamic forces on the pipeline and the spoiler as well as the local scour around the submarine pipeline. The corresponding numerical results show that the mean drag coefficients of the pipeline and the spoiler increase with the increase of the spoiler length. As for the mean lift coefficient, a general decreasing trend with the increasing spoiler length is observed for the pipeline. However, the mean lift coefficient of the spoiler first increases and then decreases with the increasing spoiler length. In addition, it is found that a larger spoiler length leads to a deeper scour depth, and an empirical equation was proposed for predicting the non-dimensional scour depth of submarine pipelines with non-dimensional spoiler length based on the numerical results.

scholarly journals Results of experimental studies and numerical modeling of multistage waveguide-slotted membranes filters with complex slots geometry

2018 ◽  
Vol 158 ◽  
pp. 01018
Author(s):  
Natalia Kopylova ◽  
Alexei Kopylov ◽  
Yuri Salomatov
Keyword(s):  
Numerical Simulation ◽  
Experimental Study ◽  
Numerical Modeling ◽  
Experimental Studies ◽  
Frequency Characteristics ◽  
Frequency Range ◽  
Waveguide Filters

The article contains the results of an experimental study and numerical simulation of the amplitude-frequency characteristics of one, three and four-stage filters on waveguide-slotted membranes with complex resonance slot geometry membranes located in a rectangular 35x15 mm waveguide. The design of filters and the topology of a complex slot in the membrane are shown. The results can be useful in the design of waveguide filters in the frequency range 5.5 … 8.5 GHz.

scholarly journals Prediction of maximum scour depth around piers with debris accumulation using EPR, MT, and GEP models

2016 ◽  
Vol 18 (5) ◽  
pp. 867-884 ◽  
Author(s):  
Mohammad Najafzadeh ◽  
Mohammad Rezaie Balf ◽  
Esmat Rashedi
Keyword(s):  
Polynomial Regression ◽  
Gene Expression Programming ◽  
Laboratory Data ◽  
Experimental Studies ◽  
Local Scour ◽  
Bridge Piers ◽  
Scour Depth ◽  
Effective Parameters ◽  
Pier Scour ◽  
Debris Accumulation

Pier scour phenomena in the presence of debris accumulation have attracted the attention of engineers to present a precise prediction of the local scour depth. Most experimental studies of pier scour depth with debris accumulation have been performed to find an accurate formula to predict the local scour depth. However, an empirical equation with appropriate capacity of validation is not available to evaluate the local scour depth. In this way, gene-expression programming (GEP), evolutionary polynomial regression (EPR), and model tree (MT) based formulations are used to develop to predict the scour depth around bridge piers with debris effects. Laboratory data sets utilized to perform models are collected from different literature. Effective parameters on the local scour depth include geometric characterizations of bridge piers and debris, physical properties of bed sediment, and approaching flow characteristics. The efficiency of the training stages for the GEP, MT, and EPR models are investigated. Performances of the testing results for these models are compared with the traditional approaches based on regression methods. The uncertainty prediction of the MT was quantified and compared with those of existing models. Also, sensitivity analysis was performed to assign effective parameters on the scour depth prediction.

scholarly journals FVCOM model simulation of local scouring around bridge pile

2019 ◽  
Vol 270 ◽  
pp. 04020
Author(s):  
Sony Herdiansyah ◽  
Dantje Kardana Natakusumah ◽  
Dhemi Harlan
Keyword(s):  
Time Series ◽  
Model Simulation ◽  
Horseshoe Vortex ◽  
Local Scour ◽  
Navier Stokes ◽  
Average Error ◽  
Scour Depth ◽  
Study Objective ◽  
Numerical Result ◽  
Study Results

Scouring is one of many damages that water can cause. Scouring can occur as a consequence of bridge pile existence. The problem on local scour around single pier will be studied by using FVCOM numerical model. This study objective is to find out how accurate FVCOM model to predict local scour behavior. FVCOM model is based on the finite volume method to solve Navier Stokes, Meyer Peter Muller, and Exner equations. FVCOM computed numerical result then will be verified with computed and measured data in previous numerical (FSUM model) and experimental study. Results from this study show FVCOM model were successfully simulated typical features of local scour around piers such as downflow and wake vortex, but failed to simulate horseshoe vortex. Both computed numerical (FSUM and FVCOM) results are then compared with measured experimental data for its magnitude and time-series of maximum scour depth. FVCOM result shows value 0.99 r-squared correlation and 5.96 percent average error, and FSUM result shows value 0.98 r-squared correlation and 6.82 percent average error. Therefore, it can be deduced that FVCOM successfully predict local scour depth and its time-series and proven that FVCOM is more accurate than FSUM model.

A novel boosting ensemble committee-based model for local scour depth around non-uniformly spaced pile groups

2021 ◽  
Author(s):  
Iman Ahmadianfar ◽  
Mehdi Jamei ◽  
Masoud Karbasi ◽  
Ahmad Sharafati ◽  
Bahram Gharabaghi
Keyword(s):  
Local Scour ◽  
Scour Depth ◽  
Pile Groups
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