NUMERICAL MODELING OF FLOW PATTERN AND BED EVOLUTION AROUND SPUR-TYPE STRUCTURES

摘要

The important parameters for designing spurs, groynes, cross-bars and abutments are the local scour depth, scour rate and the extent of scour hole which control the cost-effectiveness and performance of such structures. Existing empirical equations used for scour estimation show high level of uncertainty in prediction which are developed mainly based on laboratory experiments in straight sand-bed flumes. This study investigates different aspects of three-dimensional numerical modeling of flow and scour around spur-dikes. The model was based on finite volume technique which solves Navier-Stokes equations on a three-dimensional structured non-orthogonal boundary-fitted grids. The model computes Reynold's stress term with standard k-ε model and the sediment transportation are calculated with van Rijn's equations. Modeling of scour for unsubmerged and submerged spurs with graded sediment have been carried out. The simulated scour and shapes of scour holes are comparable to laboratory observations. Sensitivity of the model with respect to input parameters have been examined. The results show the possibility of simulating local scour in complex flow situation with the model, especially now that the cost of high performance computation has been reduced considerably.