Living Dikes are nature-based coastal defense systems that integrate engineered dikes with vegetated foreshores, such as salt marshes. These systems provide a sustainable alternative to traditional flood defenses, enhancing protection through the wave damping capacity of salt marshes while also offering ecological and climate-resilience benefits. As climate change increases the frequency and intensity of storm events and drives sea-level rise, nature-inclusive solutions like Living Dikes are becoming increasingly important for coastal resilience.
To understand and optimize their design, detailed numerical modeling is urgently needed. Computational Fluid Dynamics (CFD) models are powerful tools for simulating complex wave-vegetation-dike interactions, offering insights into wave attenuation, hydrodynamic forces on the dike, and the resulting potential erosion at critical locations such as the dike toe. OpenFOAM, a widely used open-source CFD solver, is well suited for coastal and hydraulic applications due to its flexibility, detailed physics, and large user community. However, it can be computationally expensive in some cases.
Despite growing interest in Living Dikes, a research gap remains in fully capturing the integrated effects of vegetation characteristics; such as vegetation height, stem thickness, root spacing, branch density, intertwining length, and stem flexibility on wave attenuation and their subsequent influence on dike overtopping, safety, maintenance needs, and resilience under climate extremes. This MSc project aims to address that gap.
The CFD model used in this project builds on a coupled wave-vegetation-dike model currently under development by postdoctoral researcher Paran Pourteimouri using OpenFOAM (see Figure 1 for the model geometry). The MSc student will use and adapt this existing model to explore how different vegetation traits influence hydrodynamic performance.
Key objectives:
- Apply a validated OpenFOAM model to simulate wave interactions with different designs of vegetated foreshores in front of a dike.
- Analyze the influence of vegetation characteristics (vegetation height, stem thickness, root spacing, branch density, intertwining length, and stem flexibility) on wave attenuation, bed shear stress, and hydrodynamic loading on the dike.
- Identify and quantify the relationships between vegetation properties and hydrodynamic responses in order to end up with design guidelines.
The findings are expected to provide valuable input for future developments, such as improving vegetation parameterizations in large-scale models like SWAN and Delft3D, although implementing these parameterizations is beyond the scope of this MSc project.
Expected skills:
- We are looking for an enthusiastic MSc student with a strong interest in coastal dynamics, eco-engineering design of hydraulic structures, mathematics and numerical modeling.
- Prior experience with Python or MATLAB is required, as these will be used to develop pre- and post-processing scripts that support simulation workflows and result analysis.
- Familiarity with OpenFOAM is not required and will be developed during the project.
- The student will collaborate with researchers from the Marine and Fluvial Systems (MFS) group at the University of Twente, as well as researchers from Deltares, gaining experience in applied research within a multidisciplinary team.
(a)
(b)
(c)
Figure 1. (a) 3-D view of the vegetation-dike model geometry that will be used to simulate combined wave-current flow in OpenFOAM. Vegetation is initially modelled as rigid; flexibility will be introduced later. From the offshore boundary toward the landward end, the domain layout is: a foreshore with two slopes (
transitioning to 
), then a vegetated platform placed on a 
m cliff (referenced to 
m), and finally the dike at the end of the domain with a 
slope. (b) Side view of the vegetation geometry. (c) 3-D zoomed view of (b). The current vegetation geometry is inspired by Spartina anglica, but the model framework is flexible and user-defined functions allow replication of other salt-marsh species with modifiable properties (e.g. vegetation height, stem thickness, root spacing, branch density, and intertwining length).
Supervision
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