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In a series of previous posts, we highlighted the benefits of CFD as applied to the design of new wastewater treatment plants (WWTP) or the expansion of existing ones. However, there are numerous other industrial applications that can also benefit from the accurate CFD predictions of free surface flows for influent structures. One of these industries is the Oil Sands, which has very water intensive processing facilities that recycle 80% of the water utilized.

A particularly challenging installation that Coanda analyzed was a recycle water intake which had specific inlet constraints based on the recycle pond design and a raw water inlet. The ANSI/HI 9.8-2012 guidelines for rectangular intakes with a large 72-inch diameter single suction inlet could not be fulfilled as the main sluice gate inlets from the pond were about 7m above the floor of the intake structure and could not be altered. Furthermore, there was also a 36-inch diameter raw water inlet pipe through which the remaining 20% of the water for the processing facility flowed into the intake structure. CFD simulations of the original inlet design indicated that the approach velocities to the 72-inch diameter suction inlet far exceeded the 0.5 m/s limit of the ANSI standard and jets from the sluice gate openings persisted all the way to the suction inlet, likely resulting in the formation of large surface vortices.

The only practical way to deal with the severely maldistributed inflow was to design a Formed Suction Intake (FSI). This type of intake is quite insensitive to the direction of approach flow and can also tolerate skewed velocity distributions at its entrance. Based on the FSI design recommendations set forth in the ANSI standard, CFD simulations for an FSI showed that the outlet velocity profile within the suction inlet pipe was essentially the same for all inlet conditions. This illustrates once again the utility of CFD predictions in the water flow analysis for a wide range of industrial applications.