American Society of Civil Engineers

A 3D CFD Model Investigation of an Outfall Reservoir Hydraulics for Repowering a Power Plant

by Liaqat A. Khan, (ENSR, 9521 Willows Road NE, Redmond, Washington 98052), Edward A. Wicklein, (ENSR, 9521 Willows Road NE, Redmond, Washington 98052), and Mizan Rashid, (ENSR, 9521 Willows Road NE, Redmond, Washington 98052)
Section: Applied Computational Hydraulics to Meet Environmental Challenges, pp. 1-10, (doi:

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Document type: Conference Proceeding Paper
Part of: World Environmental and Water Resources Congress 2006: Examining the Confluence of Environmental and Water Concerns
Abstract: A three-dimensional (3D) computational fluid dynamics (CFD) model of an outfall system, discharging cooling water to a reservoir through an existing outfall structure and a proposed diffuser, is presented in this paper. A repowering of the plant would increase the discharge from 55 m3/s to 76.5 m3/s. The CFD model used for the study consisted of over 1.3 million computational cells, with grid spacing varying from 0.05 m to 2.5 m. For the existing conditions, the model results indicated that a high velocity jet from the outfall structure was deflected southward and the jet impinged the southern embankment. To minimize potential erosion, the ports of the diffuser were designed to discharge water towards the water surface with a northward velocity component. With such a diffuser, model simulations indicated a significant reduction in velocities near the southern embankment. The 40 percent increase in the outfall discharge did not significantly increase the maximum near bed velocities in the reservoir.

ASCE Subject Headings:
Power plants
Three-dimensional models