Three-dimensional modelling of secondary flow in river bends

The flow in a river bend has a large influence on the cross-sectional profile of the bend. Due to the curvature of the bend a secondary flow, which is perpendicular to the main flow, occurs. The secondary flow is directed outwards in the upper part of the cross-section and inwards in the lower part of the cross-section. It causes by means of the...

Morphological modelling with suspended sediment transport in river bends

Depth-averaged morphological computations using Delft3D tend to produce ‘strange’, results for river bends when the sediment transport formulas of Van Rijn are used. Even pools in inner bend regions and bars in outer bend regions can result from the model. The objective of the present thesis is to identify the cause of the problem and propose...

Tidal Meanders in the Ameland Basin: A study to the underlying processes in the evolution of tidal meanders

The fairway connecting Holwerd and Nes forms the main transport route between Friesland and Ameland (the Dutch Wadden Sea). It consists of several tidal channels that funnel the majority of the tidal currents propagating through the tidal basin. Over the past decades, several channel bends have expanded leading to a fairway length-increase of...

Secondary Flow Mitigation in Turbine Vanes Through Endwall Fence Shape Optimization

The threat of global warming made the increase of efficiency a crucial objective for future power plants and aero engines. As secondary flow is a major source of aerodynamic losses in turbines, its mitigation is critical to enable efficient designs. However, the suppression of secondary flow formation is challenging due to the complexity of the...

A new modelling method for representing the effect of spiral flow on the bed shear stress

This thesis presents a new methodology for representing the effect of spiral flow on the bed shear stress magnitude and direction, using a low-vertical-resolution three-dimensional model. Furthermore, it discusses the performance of the new methodology in comparison with conventional high-vertical-resolution three-dimensional and depth-averaged...

Modeling Leakage Losses and Axial Thrust in Rocket Engine Turbopumps: Development of a numerical model

Large-scale liquid rocket engines require high-speed turbopumps to inject cryogenic propellants into the combustion chamber. Modeling the impact of secondary path and leakage flows on the performance and axial thrust of the pump is critical during the early design phase. Previous studies derived simplified models and empirical correlations to...