IGF

The focus of IGF Jena's work in RETERO is the investigation of fish behavior under hydraulic conditions similar to those found in turbine and pump inlets. Based on the results, behavioral rules are defined, which are implemented in the numerical models developed by ISUT and used to control the active probes constructed by IESY. In ethohydraulic experiments, the influence of acceleration and high flow velocities, as well as light conditions, on fish descent behavior is investigated in a test channel designed in collaboration with IWD and operated by the project partner. The movement patterns of the fish are recorded using an infrared camera system and analyzed using 3D tracking software. In addition, IGF Jena uses the sensor technology originally built for the robot fish by Tallinn University of Technology to develop an external sensor for fish in collaboration with this research partner to record environmental impacts on fish during turbine and pump passages. Its innovative design allows for non-invasive attachment to the dorsal fin of the fish, and the sensor can be reused after re-capturing the test fish. The attachment mechanism is designed to be variable, allowing it to be attached to almost any species of fish.

IWD

After jointly designing a test course with IGF and ISUT, IWD is responsible for the construction and operation of the physical model in the hydraulic engineering hall according to the requirements of the research subject. A 3D video tracking system developed in close cooperation with IGF is used to investigate fish behavior. The model hydraulic measurements are taken using LDA and ADV methods. This allows the fish behavior evaluated using the tracking system to be compared with the hydraulics, and specific reaction patterns can be defined for implementation into the partner tools (robot fish, numerical simulation, damage prognosis models).

ISUT

ISUT is developing a prediction model to assess the risk of fish injury during the passage of hydraulic structures. The model is based on the coupling of numerical fluid dynamics (CFD) and the discrete element method (DEM). The CFD calculates the fluid fields of the hydraulic structures, while the DEM simulates the motion of individual particles through the fluid. The particles serve as fish surrogates. The developed model allows for the active guidance of fish surrogates through the flow. Behavioral rules have been defined to enable the particle to exhibit ethohydraulically relevant fish behavior. The model also records contact interactions between fish particles and the environment (such as turbine blades or the housing wall of a hydraulic structure). The recorded data provides the opportunity for statistical evaluation and identification of critical areas in the design of hydraulic structures.

IESY

IESY contributes to the project through experimental investigations on fish surrogates and robots. The active probes developed by the department are used for the simultaneous determination and complementation of the numerics and to avoid the current practice of injecting live fish into turbines and capturing them at the outlet to determine injury risk. By mimicking relevant fish behavior (rheotaxis), they are intended to provide more accurate data on the risk of injury to fish during turbine passages than is possible with passive probes. The contribution of IESY is divided into two aspects: first, systems and methods are developed, including hardware and software for actuators and sensors, control algorithms, real-time methods for data processing, and algorithms for data fusion. Second, experiments are planned and conducted, followed by data analysis and model building. The models should replicate the correlation between sensor or simulation data and fish injuries. IESY works very closely with Taltech, whose sensors are used in the project. IGF supports IESY with its practical experience and biological expertise in impact tests and the optimization of the robot fish.

SJE

The main tasks of SJE GmbH in the RETERO project are a) to identify the relevant environmental parameters for fish behavior and b) to describe their correlation with the reactions and movements of the fish. With the knowledge gained, a probabilistic model will be designed, developed and validated to predict fish behavior under extreme hydrodynamic stresses, as they occur in and around turbines and pumps. SJE works closely with IWD, IGF, ISUT, and Taltech to fulfill a challenging task: to combine and link large amounts of data from highly diverse sources into an analysis system. This includes measurement data from laboratory experiments, model data from 2D and 3D hydrodynamic calculations, and data from the video system for recording fish positions. A specially programmed software allows for the linkage of sensorically measured and calculated parameters with fish positions, and also enables the evaluation of important fish behavior-relevant parameters, such as swimming speed or the spatial velocity gradient (SVG) along the fish body. The relevant parameters and associated fish positions are visualized in QGIS as maps or videos, which can be overlaid with the distributions of hydrodynamic parameters, for example. This information is the most important basis for interpreting the behavior of the fish in the laboratory channel and forms the basis for the implementation and validation of the prediction model, which is carried out in close collaboration with IGF.