POSTED: 14 February 2024
CLOSING DATE: 30 April 2024
ROTTERDAM, NETHERLANDS
MISSION TO METRICS
The Ocean Cleanup develops solutions to rid the world’s oceans of plastic. To do so, we design our systems as a floating barrier mounted with a permeable screen to intercept, concentrate, and extract plastics from the marine environment. To build the future Digital Twins (DT) of our cleanup systems, we want to understand better the ocean's screen dynamics and its efficiency in capturing floating plastic debris. This internship will give the opportunity to address how to accurately model a screen and predict its capturing efficiency with a state-of-the-art numerical approach.
“The understanding of how the screen behaves in the vertical direction and how the plastics interact with it are paramount for the capture efficiency of the cleanup systems. These are very hard to measure in the field, so numerical models can be very insightful.” - Andriarimina Rakotonirina, Computational Modeling Specialist
THE ASSIGNMENT
The screen is one of the most important components of our cleanup systems as it is used to funnel floating plastic marine debris toward the retention zone. Apart from the floaters that hold it at the ocean surface, it has its own dynamics. Its motion can be very different from the floaters' motion. Therefore, we are working towards finding the optimal way to model the intricating behavior of the screen as it reacts to the surrounding ocean conditions. In terms of hydrodynamic numerical modeling, multiple approaches can be considered, but these approaches can differ depending on the scales of the physics that need to be solved. As a consequence of these multiple scales, the smaller the scale, the more accurate our Digital Twin and the more complex the numerical approach. In this study, we aim to improve the current state of our Digital Twin, which is based on the method commonly called CFD-DEM short for Computational Fluid Dynamics - Discrete Element Method. The idea is to solve the fluid up to the scale of a few twine sizes (2 to 4 twine thicknesses) while modeling the screen's bending, stretching, and twisting under realistic static and cyclic hydrodynamic loads to predict its plastic capturing efficiency. Firstly, for the mechanical part, the method permits building a screen consisting of virtually bonded identical spherical particles in a straight line to create the twines, making the screen mechanical and geometrical structures. These bonds are mechanical contacts governed by a numerical model that embodies a contact-stiffness model: an elastic separation and bonding model. Secondly, for the hydrodynamics part, each particle follows a hydrodynamic drag law, making them react to the surrounding fluid. Finally, the discrete floating plastics are governed by the combination of a contact model for the particle-particle interaction and a drag closure law for the fluid-particle interaction.
You are expected to:
PROFESSIONAL QUALIFICATIONS
PERSONAL QUALIFICATIONS
This assignment is supposed to start early March at the latest and you will work for 6 to 9 months with our team, based in Rotterdam, the Netherlands.
Please note that candidates are required to be enrolled at a University (Master's/PhD program) throughout the duration of the internship. The interns are expected to be available 40 hours/week throughout the duration of the internship.
CLOSING DATE: 30 April 2024
ROTTERDAM, NETHERLANDS
MISSION TO METRICS
The Ocean Cleanup develops solutions to rid the world’s oceans of plastic. To do so, we design our systems as a floating barrier mounted with a permeable screen to intercept, concentrate, and extract plastics from the marine environment. To build the future Digital Twins (DT) of our cleanup systems, we want to understand better the ocean's screen dynamics and its efficiency in capturing floating plastic debris. This internship will give the opportunity to address how to accurately model a screen and predict its capturing efficiency with a state-of-the-art numerical approach.
“The understanding of how the screen behaves in the vertical direction and how the plastics interact with it are paramount for the capture efficiency of the cleanup systems. These are very hard to measure in the field, so numerical models can be very insightful.” - Andriarimina Rakotonirina, Computational Modeling Specialist
THE ASSIGNMENT
The screen is one of the most important components of our cleanup systems as it is used to funnel floating plastic marine debris toward the retention zone. Apart from the floaters that hold it at the ocean surface, it has its own dynamics. Its motion can be very different from the floaters' motion. Therefore, we are working towards finding the optimal way to model the intricating behavior of the screen as it reacts to the surrounding ocean conditions. In terms of hydrodynamic numerical modeling, multiple approaches can be considered, but these approaches can differ depending on the scales of the physics that need to be solved. As a consequence of these multiple scales, the smaller the scale, the more accurate our Digital Twin and the more complex the numerical approach. In this study, we aim to improve the current state of our Digital Twin, which is based on the method commonly called CFD-DEM short for Computational Fluid Dynamics - Discrete Element Method. The idea is to solve the fluid up to the scale of a few twine sizes (2 to 4 twine thicknesses) while modeling the screen's bending, stretching, and twisting under realistic static and cyclic hydrodynamic loads to predict its plastic capturing efficiency. Firstly, for the mechanical part, the method permits building a screen consisting of virtually bonded identical spherical particles in a straight line to create the twines, making the screen mechanical and geometrical structures. These bonds are mechanical contacts governed by a numerical model that embodies a contact-stiffness model: an elastic separation and bonding model. Secondly, for the hydrodynamics part, each particle follows a hydrodynamic drag law, making them react to the surrounding fluid. Finally, the discrete floating plastics are governed by the combination of a contact model for the particle-particle interaction and a drag closure law for the fluid-particle interaction.
You are expected to:
- Familiarize yourself with Aspherix-CFDEM environment
- Improve the currently implemented drag closure laws to estimate the momentum transfer between the fluid phase and the discrete particles
- Validate the model with data from our experimental study
- Establish recommendations on the design of the cleanup system
- Preparing a master’s degree in mechanical-, or marine-, or aerospace engineering or equivalent with strong fluid mechanics focus.
- Knowledge of C/C++, Python and Linux/Unix-based platforms would be beneficial
- Knowledge of Parallel Computing is a plus
PERSONAL QUALIFICATIONS
- Able to perform well in a fast-paced and highly challenging environment
- Meticulous, detail oriented, structured
- Team player, diplomatic
- Excellent communication skills
- Ability to work with tight deadlines
- Intrinsic motivation to work on our ambitious and meaningful mission
This assignment is supposed to start early March at the latest and you will work for 6 to 9 months with our team, based in Rotterdam, the Netherlands.
Please note that candidates are required to be enrolled at a University (Master's/PhD program) throughout the duration of the internship. The interns are expected to be available 40 hours/week throughout the duration of the internship.