Towards full predictions of temperature dynamics in McNary Dam forebay using OpenFOAM

Abstract

Hydroelectric facilities impact water temperature; low velocities in a reservoir increase residence time and enhance heat exchange in surface layers. In this study, an unsteady three-dimensional model was developed to predict the temperature dynamics in the McNary Dam forebay. The model is based on the open-source code OpenFOAM. RANS equations with the Boussinesq approximation were used to solve the flow field. A realizable κ-ε model that accounts for the production of wind turbulence was developed. Solar radiation and convective heat transfer at the free surface were included. The result of the model was compared with the field data collected on August 18, 2004. Changes in diurnal stratification were adequately predicted by the model. Observed vertical and lateral temperature distributions were accurately captured. Results indicate that the model can be used as a numerical tool to assess structural and operational alternatives to reduce the forebay temperature.

Keywords

• three-dimensional numerical simulation
• water temperature
• reservoir
• thermal dynamics
• OpenFOAM
• McNary Dam forebay