MODELLING OF FLOW AND SCOUR AROUND THE PIERS WITH DIFFERENT GEOMETRIC SHAPES

The piers of the bridge can change the flow pattern in the river. This means the hydraulic conditions of the river can be changed, including the increased shear stress at the bottom of the river or natural channel that has the potential to cause scour. The investigation of the flow pattern around the piers on the channel is needed to consider which parts of the piers are sensitive to scour and to analyze the flow phenomena around the piers. So, this study will investigate the flow and its effect on the scour around the piers with different geometric shapes. This study uses a fluid flow model coupled to the sediment scour model, including the Meyer Peter Muller sediment transport equation. The result of this study was obtained for one circular pier; the bed load calibration parameter was 8, and the channel roughness calibration parameter was 2.5. The calculations of scour height, scour angle and flow have a fairly good similarity. Then, these calibration parameters are used to simulate flow and scour on two circular piers, two circular end piers, and two triangular end piers. The modeling results show that there are maximum scours with the same depth of 0.04 m, but the scouring patterns are different. The maximum shear stresses obtained successively by two circular end piers, two triangular end piers, and two circular piers are 0.315 N/ m2, 0.366 N/ m2, and 0.29 N/ m2. Two circular piers give a better result than two circular end piers and two triangular piers.