Free-Surface Computational Fluid Dynamics Modeling of the Spillway and Tailrace
Based on acoustic tracking and fish tagging data, the Dalles Hydropower Dam Project has been shown to have one of the highest mortality rates for juvenile salmonids on the lower Columbia River. To assist in improving fish survival at this location, PNNL applied a three-dimensional computational fluid dynamics (CFD) model to the spillway, stilling basin and tailrace zones downstream of the dam.
A free-surface CFD numerical model was applied to simulate the highly transient and turbulent flow conditions in this region. The model is based on the volume-of-fluid method and is capable of simulating sudden discontinuities in the free surface including wave breakup. The model solves the non-hydrostatic Reynolds-averaged Navier-Stokes equations over variable-sized hexahedral cells.