The current research aims to numerically predict the performance characteristics of the Oryon Water Mill. The simulation mechanism to be developed, begins at the structural solver part of a partitioned FSI solver, upon which the unique functional characteristics of the turbine are embedded. The modelling is carried out to account for the turbine’s functional characteristics like, multiple nested rigid body FSI dynamics, non-smooth dynamics and lamella partial torque contributions. The solver is built to resolve the turbine dynamics in two dimensions and re-scale the final result with respect to the turbine core height. The results of the simulation show the predicted torque to be of similar trend as that of the experimental data collected by MARIN, while being an over-prediction by a factor of two. The optimal performance range of the turbine is predicted within an error bound of 0.1RPS. The overprediction of the torque is considered to be a result of the 2D solution not accounting for the flow leakage in the third and unaccounted for direction. The time variant fluid solution is found to be unstable due to the spikes observed in the torque time signal and is a consequence of the perfect momentum sink assumption employed in the modelling of the lamella’s non-smooth dynamics. The lamella dynamics are observed to not convergence to fully periodic behaviour and the sensitivity of the lamella’s dynamics is considered to be the root cause. The velocity Verlet based structural solver does not provide fluid-structure coupling iterations, the inclusion of which, could improve the stability of the fluid solution. This endeavour establishes a foundation for the predictive numerical simulation of the OWM in the form of baseline numerical simulation results and a developed simulation framework.

River discharge is an essential parameter in morphodynamic modelling. It proves to be highly variable in both time and space. In this thesis the impact of the schematisation of time-dependent discharge series on morphodynamic change is studied. The impact is governed by several factors such as the long-term discharge statistics, and both short- and long-term sequences of discharge stages. A variable river discharge itself does not necessarily result in morphodynamic change. Changes in conveyance area and roughness are dominant sources of bed fluctuations and bed waves. Moreover, backwater dominated segments are subject to mild fluctuations in the river bed. The combination of natural variation of hydrological processes in the upstream river catchment and the absence of a significant correlation among statistical characteristics of subsequent years makes it hard for river engineers to construct discharge time series for river models that simulate morphodynamic development. The limited predictability of future discharge time series is an important source of uncertainty in model predictions. A way to estimate this uncertainty is by means of a time-consuming Monte Carlo approach, resulting in a mean long-term morphodynamic trend and the associated uncertainty. An alternative method is the application of a deterministic series for which the long-term discharge statistics are translated into a cycled annual hydrograph (CAH). It is expected to yield similar morphodynamic changes with respect to the mean trend from the Monte Carlo approach without the need for a large number of computations. However, as is demonstrated in this study, the CAH-method lacks in performance in simulating average long-term development and the amplitude of fluctuations in the river bed, especially at locations where strong sediment transport gradients are experienced. Using a simplified two-dimensional model that represents a locally widened floodplain, the impact of the included bandwidth, short-term and long-term sequences on morphodynamic change is investigated. The aim is to improve the deterministic hydrograph schematisation and to find a more convenient way to get insight into uncertainty in simulated morphodynamics. These findings result in a set of recommendations for future schematisations of discharge time series in morphodynamic river models. An improved deterministic approach is proposed. Using historical measurements of daily discharge data, years with a similar statistical maximum, mean and standard deviation can be classified. The classified years are translated into multiple cycled annual hydrographs (MCAH). By using these hydrographs, synthetic time series are constructed. Compared to the CAH-approach, the proposed MCAH-method yields a significant reduction of the root mean square error with respect to the long-term average morphodynamic trend from the Monte Carlo simulations. Moreover, the MCAH-series result in amplitudes of bed fluctuations that are closer to the response to natural discharge time series. Finally, the MCAH-series can be used to give a rough indication of the uncertainty in future morphodynamics.