Predicting fish passage through hydropower installations

This paper presents a numerical method for predicting fish trajectories through the various components of a hydropower installation. The method is based on the assumption that a fish swimming through a complex, three-dimensional flow field, obtained via a separate Computational Fluid Dynamics (CFD) calculation, can be approximated as a body of simplified, yet fish-like, geometry whose motion does not affect the pre-computed flow field. The motion of such a fish-like body is governed by a set of six ordinary differential equations for the components of its linear and angular acceleration vectors. The source terms in these equations account for the physical characteristics of the fish as well as hydrodynamic and biological forces. The proposed model may be used to identify design elements of existing projects that induce mortality as well as to evaluate the fish-friendliness of proposed re-habilitation remedies. Its potential is demonstrated by applying it to calculate fish trajectories through a Kaplan runner and a typical draft-tube geometry.