Modelling the spillway system at the Innerdalen Dam

This project was carried out by Samuel Vingerhagen, as a part of his MSc study. The purpose of the work was to investigate the accuracy of the CFD program STAR-CCM+ in computing the spillway capacity of in the reservoir Innerdalen in Norway. This had earlier been determined in a physical model study, where a rating curve had been found.

The picture shows the spillway in the dam. A "bath-tub" spillway is used, where the water runs over the edge of the spillway and into a pool, where a tunnel leads the water away to a downstream river.

Several types of grids were used in the study. This figure shows one of the most successful types, based dominantly on hexahedral cells. Contrary to grids based on tetrahedrals or polyhedrals, the grid in the figure gave better stability and accuracy.

The figure shows the velocity vectors of the water flowing over the edge of the dam. Two vertical planes are shown. The colours of the velocity denote their magnitude, with red as high velocity and blue as low velocity. Note that a two-phase situation is modelled, with air and water. Therefore, the air velocity is also shown.

The figure shows a contour map of the water level when the water is flowing into the spillway.

The resulting rating curve matched the experimental values well, both for a coarse and a fine grid. The vertical axis shows the water level in the reservoir, and the horizontal axis shows the water discharge.

We want to thank Trønderenergi AS for the data used in this study and for allowing us to publish the results.

Samuel Vingerhagens MSc Thesis (PDF, in Norwegian)

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This page was last updated: 9. August 2011