Computational Modeling of Flow and Scour around Two Cylinders in Staggered Array

• Main Authors: Hyung Suk Kim, Min Roh, Mohamed Nabi
• Format: Article
• Language: English
• Published: MDPI AG 2017-08-01
• Series: Water
• Subjects: cylinder; large eddy simulation; scour; sediment transport; staggered array
• Online Access: https://www.mdpi.com/2073-4441/9/9/654

This paper presents a numerical study on flow and local scour around two identical cylinders with diverse spacing ratios (s/D) and alignment angles (α). The spacing ratio of center-to-center distance between cylinders (s) to the cylinder diameter (D) varied from 1.25 to 5.0, including five alignment angles ranged from 0° to 90°. The detailed scour processes and information were obtained in a physics-based way by using large eddy simulation coupled with sediment transport in a Lagrangian framework and a morphodynamic model. Turbulent flow properties around two cylinders in staggered array are significantly concerned by the spacing ratio and the alignment angle which reflect complex features of evolution of scour and scour depth. The computed results exhibited the scour depth is associated with the spacing ratio and alignment angles especially at the rear cylinder. For small alignment angles, the growth rate at the rear cylinder increased as the spacing ratio increased, due to a decrease in shielding effect. As the alignment angle increased, the scour depth around the rear cylinder increased until the angle reached approximately 45°–60°. Subsequently, the scour depth decreased with the alignment angle. It also revealed that the spacing ratio was more sensitive to the maximum scour than that of the alignment angle. For (s-D)/D > 2.0, the maximum scour depth only depended on the spacing ratio.