Numerical Study of Bed Topography Variations Owing to Placement of Triad Series of Vertical Bridge Piers Installed in a 180-degree Bend with Different Relative Radii Using SSIIM Numerical Model


In this paper, the scouring around a triad series of vertical bridge piers located in a bend is investigated using SSIIM software. To this end, some of the most essential parameters such as the relative radius and the bridge pier position in both transverse and longitudinal directions to the flow have been examined. Then the bed topography variations have been detected within a flume. It is worth mentioning that the experiments have been conducted in a 180-degree sharp bend in the presence of the bridge piers. The available experimental results were used to ensure correctness of the simulated output data. Accordingly, it is evident that the simulated model not only is capable of estimating the amount of the maximum scour and sedimentation but also can effectively predict their position using an experimental model. Based on the results, it is indicated that the maximum scour depth is reported in the case of the bridge pier transverse to the flow installed at the 60-degree position of the bend with a relative radius of 5. Under these circumstances, the maximum depth of scour is evaluated to be 1.14 times the depth of flow at the beginning of the bend. Also, the maximum volume of scour around bridge piers has been detected in this case.

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The numerical model for calculating water and sedimentation in channel


Computational fluid dynamics

R :

The central curvature radius of the bend

B :

The channel width

R/B :

The relative curvature radius

Q :

The flow discharge

D :

The pier diameter

d :

The distance between the piers

Y :

The upstream flow depth

Z :

The bed topography variations

θ :

The angles from the beginning of the bend

U :

The velocity component

k :

The turbulent flow kinetic energy

P :

Total pressure

a :

The reference area equivalent to roughness height

D 50 :

The average sediment diameter

g :

Acceleration of gravity

ρ s :

Sediment density

ρ w :

Water density

τ :

Bed shear stress

τ C :

Critical bed shear stress

\(\delta_{ij}\) :

Kronecker delta

\(\varepsilon\) :

The turbulent flow kinetic energy loss

υ :

Water kinematic viscosity

υ T :

Vortex viscosity

C bed :

Near bed suspended particles concentration

q b :

Bed load

\(d_{{{\text{s}}_{1} \max }}\) :

The maximum scour depth around piers

\(d_{{{\text{s}}_{2} \max }}\) :

The maximum scour depth of the second scour hole

h max :

The maximum sedimentation height

L :

The length of the rectangle surrounding the main scour hole

W :

The width of the rectangle surrounding the main scour hole

A :

The main scour hole area

V :

The main scour hole volume


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Correspondence to Mohammad Vaghefi.

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Vaghefi, M., Moradi, S. & Abdi Chooplou, C. Numerical Study of Bed Topography Variations Owing to Placement of Triad Series of Vertical Bridge Piers Installed in a 180-degree Bend with Different Relative Radii Using SSIIM Numerical Model. Iran J Sci Technol Trans Civ Eng (2021).

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  • Scouring
  • Bed topography variations
  • Relative radius
  • 180° sharp bend
  • SSIIM model