Abstract
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.
Highlights
Among the most prominent threats to the safety of the hydraulic structures in river/coastal/ocean areas is the local scour around their underwater pillar support, many of which are cylinders
Experimental results performed by Khosronejad and Kang [12] were chosen to verify the accuracy of the sediment transport model
As seen from the above calibration, the present model is well validated, and we adopted it for the investigation of the local scour around the submerged inclined cylinder of this paper
Summary
Among the most prominent threats to the safety of the hydraulic structures in river/coastal/ocean areas is the local scour around their underwater pillar support, many of which are cylinders. The knowledge of their combined influence is limited and further research above studies show that submergence and inclination bothfor play importantinroles in the local on theThe corresponding flow structures and scour patterns is required applications the mangrove scour of a cylinder. The knowledge of their combined influence is limited and further research on the corresponding flow structures and scour patterns is required for applications in the pneumatophore [23], artificial reefs [24,25], Fish and aquatic habitat [26], and the riparian plants [21], where a submerged inclined cylinder can be a valid simplified model. It is aimed at obtaining a better understanding of the flow and the clear-water scour around a submerged inclined cylinder
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