PhD Position Fully-Resolved Simulations of Internal Flow and Erosion Mechanisms in Dikes

Would you like to work on an intriguing topic at the interface between fluid and solid mechanics? Are you interested in studying internal flow and erosion mechanisms that could lead to failure of a dike? We are looking for an enthusiastic PhD candidate to explore the physics of “Backward Erosion Piping” (BEP), a major dike failure mechanism, by employing advanced fully-resolved numerical simulations.

Job description

The subsurface of many river dikes in the Netherlands consists of a thin and relatively impermeable clay layer on top of a thick and permeable sand layer. During high water, the high subsurface pressure may cause a crack in the clay deck at the land side of the dike, allowing water from the subsurface to flow upwards and carry away sand. A hollow pipe forms in the sand layer underneath the clay deck, marking the beginning of BEP. Subsequently, the pipe gradually expands towards the water side through primary (upstream) and secondary (downstream) erosion processes, thus destabilizing the dike.

In this PhD project, you will perform a fundamental study of pipe development through novel Particle-Resolved Direct Numerical Simulation (PR-DNS) of a small-scale system mimicking conditions in laboratory experiments on BEP. The PR-DNS uses a finite-volume solver for the fluid phase, an efficient Immersed Boundary Method for the particle-fluid coupling, and a soft-sphere collision model for frictional particle contacts. The in-house code is written in modern Fortran with the MPI extension for parallel computing on supercomputers. The PR-DNS will enable a detailed study of the instantaneous, 3D flow and particle motion during BEP development.

Using this, the main aims for the project are to:

1. evaluate simplified, often 2D, models of BEP,
2. assess the influence of particle grading and solid friction on BEP, and
3. assess 3D effects such as meandering of pipes.

The research will be conducted within the Process & Energy department at TU Delft under daily supervision of Dr. Breugem and with Dr. Oldenziel (TUD/Deltares) as co-supervisor. The project is part of the Research Program ‘Digital dikes: a multiscale framework for risk assessment of Backward Erosion Piping’, consisting of a multidisciplinary consortium of academics, industry and governmental bodies. This includes 8 PhDs, 4 Postdocs and 1 EngD working at different universities across the Netherlands.

Experiments performed in a related PhD project will be used to validate the PR-DNS. Furthermore, the PR-DNS will be used to evaluate and develop closure relations for particle-particle and particle-fluid interactions needed for continuum models to simulate BEP and underground water flow at dike scale in another PhD project.

Job requirements

We are looking for a highly motivated and skilled candidate who is enthusiastic about studying the fundamental flow and erosion physics of BEP through PR-DNS. The successful candidate should have:

• An MSc degree in a relevant field (Mechanical Engineering, Applied Physics, Civil Engineering).
• Demonstrated competencies in fluid mechanics, computational fluid dynamics and scientific programming. Experience with multiphase flows, Direct Numerical Simulation, Discrete Element Modelling, Fortran, and/or parallel computing is a plus.
• The ability to work in a multidisciplinary consortium, take initiative, and be results-oriented. This also includes affinity with experiments.
• Be well organized and have excellent time management skills.
• Excellent communication skills and command of English.
• Affinity with teaching and guiding MSc students.

TU Delft as an employer

TU Delft (Delft University of Technology) is a top international university combining science, engineering and design. It delivers world-class results in education, research and innovation to address challenges in the areas of energy, climate, mobility, health and digital society.

Faculty Mechanical Engineering

The Faculty of Mechanical Engineering offers a dynamic and innovative environment with high-tech lab facilities and international reach. Its research and education focus on fundamental understanding, design, production, application and product improvement, materials, processes and mechanical systems.

Conditions of employment

Doctoral candidates will be offered a 4-year period of employment in principle, in the form of 2 employment contracts. An initial 1.5 year contract includes an official go/no go progress assessment within 15 months, followed by an additional contract for the remaining 2.5 years assuming performance requirements are met.

As a PhD candidate you will be enrolled in the TU Delft Graduate School. The TU Delft Graduate School provides an inspiring research environment with an excellent team of supervisors, academic staff and a mentor. The Doctoral Education Programme is aimed at developing your transferable, discipline-related and research skills.

The TU Delft offers a customisable compensation package, discounts on health insurance, and a monthly work costs contribution. Flexible work schedules can be arranged.

Will you need to relocate to the Netherlands for this job? TU Delft is committed to making your move as smooth as possible. The HR unit, Coming to Delft Service, offers information to help you prepare your relocation. In addition, Coming to Delft Service organises events to help you settle in the Netherlands and expand your social network in Delft. A Dual Career Programme is available to support your accompanying partner with their job search in the Netherlands.

As part of knowledge security, TU Delft conducts a risk assessment during the recruitment of personnel to help prevent the unwanted transfer of sensitive knowledge and technology. The assessment is based on information provided by candidates themselves, such as their motivation letter and CV, and takes place at the final stages of the selection process. When the outcome of the assessment is negative, the candidate will be informed. The processing of personal data in the context of the risk assessment is carried out on the legal basis of the GDPR: performing a public task in the public interest.