HR: 0800h
AN: H41A-0138    [Abstracts]
TI: On the Ability of a 2D Model for Predicting Contraction Scour
AU: * Lai, Y G
EM: ylai@do.usbr.gov
AF: Bureau of Reclamation, Bld.67(86-88540), PO Box 25007, Denver, CO 80225-0007, United States
AU: Greimann, B P
EM: bgreimann@do.usbr.gov
AF: Bureau of Reclamation, Bld.67(86-88540), PO Box 25007, Denver, CO 80225-0007, United States
AB: Contraction scour is often encountered in natural rivers due to flow area contraction or river restoration structures. Such scour may be predicted better with multi-dimensional models. However, it has been reported that the two- dimensional (2D) depth-averaged model is inadequate for modeling the contraction scour. Two potential problems of the 2D model have been identified in previous studies: inability to account for the three-dimensional (3D) effect and deficiency in the turbulence model. The finding led to efforts to use 3D models to model the contraction scour. This study aims to investigate whether other factors play important roles in the poor performance of 2D models. In the process, an improved prediction using the 2D model is obtained and factors influencing the model prediction are identified. The motivation of the study stems from the fact that a 3D model is still too complex, and many engineering applications still have to rely on 2D models. Our study shows that the 2D model is adequate for the contraction scour modeling, and comparable results with those of 3D modeling may be obtained. In addition to the 3D effect and turbulence models, other factors play important roles such as those related to the sediment transport model. Through a parametric study, the relative importance of a number of parameters is studied and suggestions are given with regard to the proper calibration and verification.
DE: 1815 Erosion
DE: 1846 Model calibration (3333)
DE: 1847 Modeling
DE: 4558 Sediment transport (1862)
DE: 4863 Sedimentation (1861)
SC: Hydrology [H]
MN: 2007 Fall Meeting