Fluid Mechanics Anlysis of Different Weir Geometry

Project Overview

This was the final group project as part of my studies in the undergraduate Fluid Dynamics class. The goal was to utilize our studies in fluid dynamics to develop an understanding of how varying the geometry of different weirs in a flume effect the flow of water.

Weirs are small dam-like structure built along streams and canals that are useful in controlling the upstream flow of water and water level. The purpose in varying the geometry of a weir is to achieve a different discharge coefficient, which is a constant specific to each geometry that impacts the flowrate of water after it passes over the weir.

To conduct our experiments, we first constructed a flume out of polycarbonate sheets and a simple electric water pump. My team and I then devised a series of experiments on four different weir geometries shown in the image carousel above. We measured the flow rate of the water exiting the each flume and then calculated the subsequent discharge coefficient. The geometries that produced lower discharge coefficients were said to perform better as this means they were able to reduce the flow rate the most.


What we found was rather counterintuitive. The height of the weir generally seemed to have the greatest impact on discharge coefficient. Beyond that, it was also found that angling the weir along the direction of flow (ie. not perfectly perpendicular) also had an effect on slowing the exit flow.

All in all, these experiments were an incredibly introduction into fluid dynamics. The most exciting takeaway from this project was the ability to witness fluid mechanics calculations in practice!


Final Presentation: Short video presenting our findings and calculations