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 in order to intercept it with our cleanup systems. This position provides the opportunity to address how the modeling of plastic particles with inertia exhibits distinct dynamics, compared to simple passive tracers, leading to clustering and preferential concentration in a vortex field.Â
THE ASSIGNMENT
The Ocean Cleanup relies on Ocean General Circulation Models (OGCMs) to describe physical ocean processes that help track 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 an energy cascade (the largest scales provide energy that drives small-scale processes), namely the mesoscale and submesoscale. In the plastic marine debris tracking context, the submesoscale plays a significant role in their transport since the convergence zones therein might trap or spin plastic debris and carry it into large gyres. From the modeling point of view, these OGCMs cannot resolve small-scale flow features due to computational limits, often limited to O(1) km grid resolution. As the plastics that are catchable by our cleanup systems are in the O(1) m and the flow features of the submesoscale processes are in the same order of magnitude or higher, it is important to evaluate the plastic transport on this scale. In this study, we intend to get valuable statistics on eddy trapping, residence time, dispersion rates, and clustering patterns of inertial particles using a 2D Navier-Stokes flow solver (Basilisk) that can capture the main eddy scales. As a purely 2D approach omits vertical processes, we aim to create an idealized horizontal mixing scenario. We will extract surface-layer velocities from an ocean model (HYCOM, etc.) for the focused region, the Great Pacific Garbage Patch (GPGP), and use them as initial conditions of our 2D Navier-Stokes flow solver either for a decaying or a forced turbulent flow. This will help us quantify the inertial plastic marine debris transport mechanism in a 2D vortex field where the flow characteristic length scales are greater than one or two orders of magnitude larger than the particle size. From this approach, we will gain valuable insights into horizontal dispersion statistics, clustering statistics, inertial effects, and especially patch formation as a function of the vorticity intensities that are important for our mission.Â
You are expected to:Â
PROFESSIONAL QUALIFICATIONSÂ
PERSONAL QUALIFICATIONSÂ
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 in order to intercept it with our cleanup systems. This position provides the opportunity to address how the modeling of plastic particles with inertia exhibits distinct dynamics, compared to simple passive tracers, leading to clustering and preferential concentration in a vortex field.Â
THE ASSIGNMENT
The Ocean Cleanup relies on Ocean General Circulation Models (OGCMs) to describe physical ocean processes that help track 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 an energy cascade (the largest scales provide energy that drives small-scale processes), namely the mesoscale and submesoscale. In the plastic marine debris tracking context, the submesoscale plays a significant role in their transport since the convergence zones therein might trap or spin plastic debris and carry it into large gyres. From the modeling point of view, these OGCMs cannot resolve small-scale flow features due to computational limits, often limited to O(1) km grid resolution. As the plastics that are catchable by our cleanup systems are in the O(1) m and the flow features of the submesoscale processes are in the same order of magnitude or higher, it is important to evaluate the plastic transport on this scale. In this study, we intend to get valuable statistics on eddy trapping, residence time, dispersion rates, and clustering patterns of inertial particles using a 2D Navier-Stokes flow solver (Basilisk) that can capture the main eddy scales. As a purely 2D approach omits vertical processes, we aim to create an idealized horizontal mixing scenario. We will extract surface-layer velocities from an ocean model (HYCOM, etc.) for the focused region, the Great Pacific Garbage Patch (GPGP), and use them as initial conditions of our 2D Navier-Stokes flow solver either for a decaying or a forced turbulent flow. This will help us quantify the inertial plastic marine debris transport mechanism in a 2D vortex field where the flow characteristic length scales are greater than one or two orders of magnitude larger than the particle size. From this approach, we will gain valuable insights into horizontal dispersion statistics, clustering statistics, inertial effects, and especially patch formation as a function of the vorticity intensities that are important for our mission.Â
You are expected to:Â
- Familiarize with Basilisk environment and run Basilisk simulations
- Do statistical analysis on inertial particles:Â
- clustering in regions of various vorticityÂ
- velocity and acceleration in these regionsÂ
- residence time in these regionsÂ
- interaction with various eddy scales
- Suggest description of inertial particles transport stemming from high resolution vortex fields Â
- Currently in a master program in aerospace or mechanical engineering with a strong focus in fluid mechanicsÂ
- Knowledge of Basilisk is beneficial Â
- Knowledge of C/C++ (language of Basilisk), Python and Linux/Unix-based platforms would be beneficialÂ
- Knowledge of High-Performance Computing is a plusÂ
PERSONAL QUALIFICATIONSÂ
- Able to perform well in a fast-paced and highly challenging environmentÂ
- Meticulous, detail-oriented, structuredÂ
- Team player, diplomatic Â
- Excellent communication skillsÂ
- Ability to work with tight deadlinesÂ
- Intrinsic motivation to work on our ambitious and meaningful missionÂ
- Â Starting date: As soon as possible
- Duration: 6 months
- WORK PERMIT NEEDED: European Union
- At The Ocean Cleanup, we believe we are stronger together while harnessing the uniqueness each individual brings. That is why we take a fair, equal opportunity, and transparent approach to hiring and welcome special needs requests.
Curious to hear how it is to work at The Ocean Cleanup? Listen to our team members explain their work in our podcast.