The Ocean Cleanup develops and scales technologies to rid the world’s oceans of plastic. To do this, we design our systems as a floating barrier mounted with a fishing-net like skirt to intercept, concentrate and extract plastics from the marine environment. In an effort to build the future Digital Twins (DT) of our cleanup systems we want to better understand the dynamics of the net in the ocean and its efficiency in capturing floating plastic debris. This internship will give the opportunity to address how to accurately model a net and predict its capturing efficiency with a state-of-the-art numerical approach.
A net is one of the most important components of our cleanup systems as it is used to intercept floating plastic marine debris. Apart from the floaters that hold the net in the ocean, it has its own dynamics. In fact, its motion can be very different from the floaters motion. Therefore, we are working towards finding the optimal way to model the intricating behaviour of the net as it reacts to the surrounding ocean conditions. In terms of hydrodynamic numerical modelling, there are multiple approaches that 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 is our Digital Twin but also the more complex the numerical approach. In this study we aim at solving the fluid up to the scale of few twine sizes (2 to 4 twine thicknesses) additionally we aim at modelling the bending, the stretching, and the twisting of the net under realistic static and cyclic hydrodynamic loads to predict its plastic (modelled as discrete floating particles) capturing efficiency. This approach is possible thanks to the well know method in the field of multiphase flow commonly called CFD-DEM short for Computational Fluid Dynamics - Discrete Element Method. Firstly, for the mechanical part, the method permits to build a net consisting of identical spherical particles in a straight line and virtually bonded to create the twines making the net mechanical and geometrical structures. These bonds are contacts governed by a numerical model which embodies a contact-stiffness model, an elastic separation model and a bonding model. Secondly, for the hydrodynamics part, each individual 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:
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.
The Ocean Cleanup develops advanced technology to extract, prevent, and intercept plastic pollution. Our goal is to initiate the largest cleanup in history by mid-2018.