Turbulent eddy identification of a meander and vertical-slot fishways in numerical models applying the IPOS-framework

Abstract Fishways are an important link for the reestablishment of river continuity, interrupted by transverse structures e.g. weirs, dams and hydropower plants. The meander fishway and vertical slot fishway are two types commonly constructed in Germany, which create distinctive flow regimes to allow upstream passage. Nonetheless minor environmental or constructional alterations create unforeseen flow regimes, whose impact on fish behaviour is still uncertain. One approach is to obtain different flow aspects for fish by evaluating numerous parameters with the IPOS-framework in laboratory experiments. The framework provides various identification parameters and methods, which must be considered with regard to fish behaviour. This paper expands the experimental approach by using numerical simulations with OpenFOAM on one meander and two vertical slot fishways and employs the evaluation methods stated in the IPOS-framework. The results shows clear differences between the fishways, providing an advanced numerical evaluation method to objectively compare turbulent flows in the models. The 3D-hydronumerical evaluation of 1:1 scaled fishways using the IPOS-framework is a novelty so far and can be used to improve present and future fishway constructions.