Internship - Computational Modelling
The Ocean Cleanup
Posted on Oct 23, 2025
MISSION TO METRICS
The Ocean Cleanup develops solutions to rid the world’s oceans of plastic. To do so, we need to understand the dynamics of floating plastic marine debris in the ocean environment to intercept them with our cleanup systems. This position will give the opportunity to address the aerodynamic drag of large plastic marine debris at the ocean surface due to air exposure, influencing the transport, dispersion, and accumulation of plastics, with significant implications for modeling its distribution.
THE ASSIGNMENT
The Ocean Cleanup relies on Lagrangian Particle Tracking and Ocean General Circulation Models (OGCMs) to describe physical ocean processes that help understanding the transport of plastic marine debris in the Great Pacific Garbage Patch (GPGP). These models account for a wide range of interacting physical processes that occur across spatial and temporal scales. These oceanic processes span several orders of magnitude in both space and time: microscale (1 mm to 1 cm, seconds to minutes), submesoscale (1 km to 10 km, hours to days), mesoscale (10 km to 100 km, days to months) and global scale (1000 km to 10,000 km, years to decades). The interaction between these scales is mainly governed by energy cascade (the largest scales provide energy that drives small scale processes). Additionally, we would like to advance our understanding of the role of wind in driving the transport of floating plastic debris at the ocean surface, with a particular emphasis on the aerodynamic drag acting on large, partially submerged objects. While ocean currents and waves are known to dominate the large-scale movement of plastics, the influence of near-surface winds is significant at submesoscale and mesoscale levels, and its cumulative effect can extend to basin and even global scales by altering the dispersion, accumulation, and eventual fate of plastics. To capture these processes more accurately, we will employ Computational Fluid Dynamics (CFD) tools such as Basilisk, which allow high-fidelity simulations of multiphase flows. We will design and run numerical experiments to quantify drag coefficients for representative debris shapes, considering the exposure of plastics above the free surface. Special attention will be given to applying appropriate boundary conditions, in particular the representation of the Atmospheric Boundary Layer (ABL), which governs the velocity profiles of winds acting on exposed surfaces. By combining CFD-derived drag estimates with simplified parameterizations, the results can be integrated into Lagrangian transport models, enabling sensitivity studies on how windage influences dispersal patterns across scales.
You are expected to:
PROFESSIONAL QUALIFICATIONS
The Ocean Cleanup develops solutions to rid the world’s oceans of plastic. To do so, we need to understand the dynamics of floating plastic marine debris in the ocean environment to intercept them with our cleanup systems. This position will give the opportunity to address the aerodynamic drag of large plastic marine debris at the ocean surface due to air exposure, influencing the transport, dispersion, and accumulation of plastics, with significant implications for modeling its distribution.
THE ASSIGNMENT
The Ocean Cleanup relies on Lagrangian Particle Tracking and Ocean General Circulation Models (OGCMs) to describe physical ocean processes that help understanding the transport of plastic marine debris in the Great Pacific Garbage Patch (GPGP). These models account for a wide range of interacting physical processes that occur across spatial and temporal scales. These oceanic processes span several orders of magnitude in both space and time: microscale (1 mm to 1 cm, seconds to minutes), submesoscale (1 km to 10 km, hours to days), mesoscale (10 km to 100 km, days to months) and global scale (1000 km to 10,000 km, years to decades). The interaction between these scales is mainly governed by energy cascade (the largest scales provide energy that drives small scale processes). Additionally, we would like to advance our understanding of the role of wind in driving the transport of floating plastic debris at the ocean surface, with a particular emphasis on the aerodynamic drag acting on large, partially submerged objects. While ocean currents and waves are known to dominate the large-scale movement of plastics, the influence of near-surface winds is significant at submesoscale and mesoscale levels, and its cumulative effect can extend to basin and even global scales by altering the dispersion, accumulation, and eventual fate of plastics. To capture these processes more accurately, we will employ Computational Fluid Dynamics (CFD) tools such as Basilisk, which allow high-fidelity simulations of multiphase flows. We will design and run numerical experiments to quantify drag coefficients for representative debris shapes, considering the exposure of plastics above the free surface. Special attention will be given to applying appropriate boundary conditions, in particular the representation of the Atmospheric Boundary Layer (ABL), which governs the velocity profiles of winds acting on exposed surfaces. By combining CFD-derived drag estimates with simplified parameterizations, the results can be integrated into Lagrangian transport models, enabling sensitivity studies on how windage influences dispersal patterns across scales.
You are expected to:
- Familiarize with Basilisk environment and run Basilisk simulations
- Do statistical analysis of drag coefficients depending on the flow regime and the immersion of the plastic objects
- Suggest first correlations that can be implemented into our Lagrangian Particle Tracking model to account the presence of wind
- Currently enrolled in a PhD program in aerospace or mechanical engineering with strong focus in fluid mechanics
- Knowledge of Basilisk is beneficial
- Knowledge of C/C++ (language of Basilisk), Python and Linux/Unix-based platforms would be beneficial
- Knowledge of High-Performance Computing is a plus
- 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
| Month | Task | Deliverables |
| 1 | Familiarization & Setup | Environment setup, baseline test cases, validation note |
| 2 | Initial CFD Campaign | Database of drag coefficients for simplified shapes |
| 3 | Extended CFD Simulations | Interim report with statistical distributions of drag coefficients |
| 4 | Statistical Analysis & Correlation Development | Draft correlation formulas with supporting plots |
| 5 | Integration Pathway for Lagrangian Models | Technical memo with integration parameterizations |
| 6 | Consolidation & Final Deliverables | Final report, dataset, reproducible scripts |