American Society of Civil Engineers


Validation of a 3D RANS Model to Predict Flow and Stratification Effects in River-Dam Forebays


by Md. Manjurul Haque, (Civil & Environmental Engineering and IIHR-Hydroscience and Engineering, The University of Iowa, Stanley Hydraulics Laboratory, Iowa City, IA 52242 E-mail: mhaque@engineering.uiowa.edu), George Constantinescu, (Civil & Environmental Engineering and IIHR-Hydroscience and Engineering, The University of Iowa, Stanley Hydraulics Laboratory, Iowa City, IA 52242 E-mail: sconstan@engineering.uiowa.edu), and Larry Weber, (Civil & Environmental Engineering and IIHR-Hydroscience and Engineering, The University of Iowa, Stanley Hydraulics Laboratory, Iowa City, IA 52242 E-mail: larry-weber@uiowa.edu)
Section: Hydraulics and Structures, pp. 1-12, (doi:  http://dx.doi.org/10.1061/40792(173)451)

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Document type: Conference Proceeding Paper
Part of: Impacts of Global Climate Change
Abstract: Flow and temperature distributions within the powerhouse units and the forebay of McNary Dam on the Columbia River are predicted using a fully coupled non-hydrostatic 3D Reynolds Averaged Navier Stokes (RANS) Computational Fluid Dynamics (CFD) model. The parallel pressure based solver of FLUENT is employed and the Boussinesq approximation is used to account for temperature stratification effects. The model is validated with hydrodynamics data from a 1:25 scaled model laboratory study of a single turbine powerhouse unit and temperature data collected in the forebay of the McNary Dam by the U.S. Army Corps of Engineers (USACE) in summer 2004. Excellent agreement for the velocity distributions inside the model intake unit is observed. The unstructured mesh of the full forebay simulation contains close to 6 million cells. This large size was needed to incorporate all the relevant geometrical details of the hydraulic structures and forebay bathymetry over a length of 13,000ft and to accurately resolve the large temperature gradients present near the free surface under strong stratified conditions. Overall, a good agreement is found between the simulated temperature profiles and corresponding field data inside the forebay.


ASCE Subject Headings:
Validation
Three-dimensional models
Stratified flow
Columbia River
Dams