Mohammadi Rahmatolah


Hydraulic characteristics of vertical drop pool


Student Name

Rahmatollah Mohammadi



Mohammad Reza Chamani
(Assist. Prof._Civil Engineering Department_Isfahan University of Technology)

Mohammad Karim Beirami
(Assist. Prof._Civil Engineering Department_Isfahan University of Technology)









In this study, the hydraulics of vertical drops. such as energy loss, pool depth and downstream depth have been analyzed. Both analytical and experimental procedures are considered in this study. The experiments were conducted in the Hydraulics Lab, Department of Civil Engineering, Isfahan University of Technology.

Four mathematical models are presented to evaluate drop characteristics. In the first model, Navier-Stokes equations in the cylindrical coordinate are used. This model doesn't give suitable results. The predictions of the remaining three models give good results for evaluating hydraulics characteristic of the vertical drop. In these models, the vertical drop is simulated with the free jet model. The second model is based on the assumption that the main cause for the energy loss is due to the existence of the circulating flow in the drop pool. In the third model, the component of the momentum in the downstream direction at the drop and the free jet is assumed to be equal. In the forth model, the Reynolds equations for the plane turbulent wall jet are simplified for a two dimensional flow.

The experimental results of the drop length, pool depth and length, downstream depth, and energy loss have been compared to the predictions of the presented models. For the energy loss, the predictions of the second model are fairly close to the experimental results. All models predict well the downstream depth. The estimated values of the pool depth are lower than those of the experimental data. This is because of the presence of the air in the pool circulating flow which was not considered in the models.