Turbulence effects reshape ship exhaust pollution near tankers
On the near-field evolution of a chemically reactive plume behind a ship
Computational Engineering, Finance, and Science
Summary
Pollution from big ships, like oil tankers, spreads in complicated ways very close to the ship. The authors studied how chemicals in the exhaust mix and react with the air differently than simple models predict. They used advanced computer simulations to show that small-scale turbulence strongly changes pollutants like nitrogen oxides and ozone near the ship’s exhaust. Their work helps improve future air pollution models by including these detailed mixing effects.
What this means in practice
- •For environmental engineers: Improve pollution dispersion models near large vessels by incorporating turbulence and chemistry interactions shown in this study.
- •For air quality modelers: Develop more accurate near-field ship emission simulations using the CFD-CMC-ISRN framework to refine regulatory air quality assessments.
Authors
Ramesh Kolluru, Savvas Gkantonas, B Harikrishnan, Epaminondas Mastorakos
Abstract
The near-field evolution of chemically reactive pollutants in the exhaust plume of a 270 m crude oil tanker is investigated using a high-fidelity Computational Fluid Dynamics (CFD) framework coupled with a Conditional Moment Closure (CMC) turbulence-chemistry interaction model and the CBM-IV atmospheric chemistry scheme. Two complementary approaches, a canonical zero-dimensional CMC (0D-CMC) and a spatially resolved Imperfectly Stirred Reactor Network (ISRN), quantify micromixing effects using information from the CFD flow field. Micromixing strongly modulates the evolution of NO, NO2, O3, and PAN, explaining spatial discrepancies between detailed CFD-CMC results and Gaussian plume estimates. While conventional Gaussian formulations overpredict near-field NO by up to 45% within the first 300 m, they are used here as a contextual reference to highlight where turbulence-chemistry coupling matters. The CFD-CMC-ISRN framework therefore provides a physically consistent basis for integrating micromixing effects into next-generation dispersion and air-quality models. This framework bridges the gap between combustion-derived turbulence-chemistry models and environmental dispersion simulations, enabling improved parameterization of subgrid mixing in regulatory contexts.