Comparative Study of a CFD model and a Reservoir Routing Model Predictions for Stormwater Ponds

Bernardo C. Trindade and Jose G. Vasconcelos

ABSTRACT

The hydraulic design of stormwater detention ponds is usually based on the application of different implementations of the reservoir routing approach, which in turn is essentially a discrete solution for the continuity equation. Reservoir routing approach has been successful in predicting the attenuation of the peak outflow discharge, and is implemented in computational models such as SWMM (EPA, 2005). Yet, reservoir routing models do not provide information on the velocity fields that are expected within the pond, which is a parameter that could be useful in assessing the location and extent of dead zones as well locations in which velocities may be above a desired range. Such velocity fields can be obtained with the use of more complex CFD models, but those are computational-intensive applications that may be expensive to perform. This work presents a comparative study of the flow predictions yielded by a reservoir routing method and by a 2-D CFD model for two hypothetical detention ponds. The shape and the peak discharge in the hydrographs are compared, and the location of the high and low velocities zones for each simulation condition is determined with the CFD model. The results show that the peak discharges in both methods agree very well, but there are few discrepancies in the predicted shapes of the hydrograph after the peak flow. Some of the simulated flow conditions highlight the usefulness of more sophisticate approaches to simulate flow in stormwater ponds when high velocities are anticipated.


Permanent link: