Are Integral Wing Walls Necessary For Flumes?

One question we get asked time and time again is: do I need fiberglass / galvanized / stainless steel wing walls for my fiberglass / galvanized / stainless steel flume or can I just form them on my own?

The short answer is no, they don’t need to be made of the same material as the flume and yes you can form them yourself. The longer answer can be a little more complicated…

Galvanized Steel 1.5' H-Flume with Inlet Wing Walls

Fundamentally, all a wing wall is designed to do is to direct water into / out of a flume in a controlled way. Naturally, wing walls needs to be wide enough to span the full width of the channel so that all of the flow is directed into the flume. Further, the wing walls must be watertight at its junction with the entrance of the flume. In both width of span and watertight connection to the flume, the concern is that flow does not bypass the flume – that all of the flow is accounted for and that scouring around the flume does not occur.

Cutthroat Flume with Customer Installed Wing Walls

Fiberglass 108

Wing walls are not integral to the actual development of curvilinear flow in the flume - they are transition pieces only. This is not to say, though, that poorly formed inlet wing walls cannot affect flow accuracy - quite the contrary. Research and field observations have shown the 45º flat wing walls can develop a wave / trough phenomena that can affect accuracy head measurement as flow rates rise. Now properly radiused wing walls can be tricky to form in the field which is a reason when they are used, they are almost always supplied with the flume.

Fiberglass 24

So long as wing walls are properly formed, span the necessary channel width, and are watertight, whether they are made from the same material as the flume they are attached to is irrelevant. For convenience, some customers insist that wing walls are integral to the flume - allowing them to set the entire structure at once.