In wastewater treatment plants, it is critical to split the incoming flow evenly into separate channels for processing downstream. If the flow split is uneven, one or more streams could be undertreated, resulting in a final effluent of reduced quality. This is especially pertinent for a new wastewater treatment plant being built in Auckland, New Zealand, from which effluent will dis- charge into the Hauraki Gulf, teeming with marine life and fre- quented by swimmers. To achieve even flow splitting, engineers from URS Corporation worked with CFD-RES consultants to redesign the flow splitter that would be used.

Velocity contours through the splitter after the semicircular insert was added

In this splitter, water travels through a mitered bend of a pipe to flow vertically upward into a chamber. It then discharges over its four sides via weirs into separate streams.The engineers suspected that the water would accelerate around the bend of the pipe and preferentially discharge over one of the four sides. The CFD-RES consultants carried out a 3D FLUENT simulation that confirmed this suspicion. To achieve a more even distribution, a semi-circular insert was proposed to force the flow into the central region of the chamber. Different thicknesses of this insert were investigated to ensure even flow rates over the four weirs. The simulations proactively determined potential design flaws, which the engineers were able to correct prior to final construction, thereby saving unnecessary time and expense for a retrofit once the plant was operational.

The revised flow splitter design prior to installation in the wastewater treatment plant

FluentNEWS