Outlet Scour Modeling for Drop Height Influence

Abstract

Modeling of scour below pipe outlets has received considerable attention in the literature. However, there has been disagreement regarding the inclusion of the effect of drop height in the modeling procedure. For the purpose of obtaining scour dimensions for various drop heights, adjustment factors are provided in the literature that, when multiplied with the scour dimensions based on zero height, account for the influence of drop height. From the use of these coefficients, it was observed that the influence of drop height was not represented satisfactorily. There is apparently a need to reanalyze the existing data to determine the influence of drop height on outlet scour. Also, the issue of drop height referencing has not been addressed in earlier studies. This has resulted in inconsistent use of the drop height term. With this in view, various strategies were employed to focus the issue of drop height referencing and its implications on outlet scour modeling. As a result, improved results were obtained in comparison with the adjustment coefficient–based approach of outlet scour modeling.