Papers

61,005 results
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Article Tier 2

Torques on curved atmospheric fibres

Researchers derived a theoretical model for how planar curved atmospheric fibers settle in quiescent air, finding that fluid-inertia torques can align asymmetric fibers at oblique angles relative to gravity — consistent with recent laboratory observations. The model demonstrates that inertial alignment is a general and important factor governing the atmospheric transport of asymmetric particles such as curved microplastic fibers and ash particles.

2024 arXiv (Cornell University)
Article Tier 2

Inertial settling of an arbitrarily oriented cylinder in a quiescent flow : from short-time to quasi-steady motion

This study modeled the inertial settling behavior of cylindrical particles — which can represent microplastic fibers — falling through still water. Researchers derived mathematical expressions for how cylinders orient and accelerate during settling at both short and long time scales. Understanding how fiber-shaped microplastics settle is important for predicting where they accumulate in aquatic environments.

2023 arXiv (Cornell University)
Article Tier 2

Low Reynolds Number Settling of Cylindrical Rods with Various Geometries in a Quiescent Fluid

Researchers experimentally investigated the settling behaviour of curved, V-shaped, U-shaped, and S-shaped cylindrical rods at low Reynolds numbers to improve models of atmospheric microplastic fibre transport, conducting experiments with millimeter-scale metal rods spanning aspect ratios from 10 to 120. The study found that fibre geometry significantly affects settling trajectories and drag compared to simplified sphere or straight-cylinder approximations used in current atmospheric transport models.

2025 York University Digital Library (York University)
Article Tier 2

Gravitational settling of microplastic fibers: experimental results and implications for global transport

This study measured the gravitational settling velocities of microplastic fibers and found that their non-spherical shape causes them to settle much more slowly than spheres of the same volume. Current atmospheric transport models that assume spherical particles significantly underestimate how long fibers remain airborne. These results have important implications for predicting how far microplastic fibers can travel before depositing.

2023
Article Tier 2

Microfiber behavior in turbulence and in quiescent conditions: insights from 3D high-speed measurements

Researchers investigated the settling dynamics of microplastic fibers with high aspect ratios under turbulent and quiescent airflow conditions, using 3D high-speed measurements to show that existing drag models fail to accurately predict settling velocities of these anisotropic curved fibers with diameters of 10-100 micrometers.

2024
Article Tier 2

Terminal Settling Velocity of Cylindrical Rods with Various Geometries Applicable to Atmospheric Microplastics

Researchers measured how the shape of cylindrical microplastic fibers affects their settling speed through air, finding that curved and V-shaped fibers fall significantly faster than straight ones — up to 57% faster for V-shaped rods — which matters for predicting how airborne microplastics disperse in the atmosphere.

2024 Proceedings of the ... International Conference on Fluid Flow, Heat and Mass Transfer
Article Tier 2

Twist, turn and encounter: the trajectories of small atmospheric particles unravelled

Experiments and simulations studied how non-spherical solid particles (including microplastics) settle through air, finding unexpectedly complex tumbling and spiraling trajectories even at low speeds. These insights improve predictions of how airborne microplastic particles travel and deposit across landscapes.

2025 Journal of Fluid Mechanics 1 citations
Article Tier 2

A physics-based and orientation-aware method for the direct calculation of  the settling speed of prolate spheroidal particles in the atmosphere : theoretical basis and comparison to laboratory and CFL data

Researchers developed a physics-based, orientation-aware method for calculating the settling speed of prolate spheroidal particles such as microplastic fibres in the atmosphere, grounding the approach in theoretical drag and orientation models rather than purely empirical fits and validating it against laboratory and CFD data.

2025
Article Tier 2

Shape matters: long-range transport of microplastic fibers in the atmosphere

This study modeled the long-range atmospheric transport of microplastic fibers, finding that their elongated non-spherical shape causes them to travel much farther than spherical particles before settling. This helps explain why microplastic fibers are found even in the most remote locations on Earth, far from any plastic pollution source.

2023 arXiv (Cornell University) 2 citations
Article Tier 2

Modeling the Gravitational Settling of Microplastic Fibers in the Atmosphere

Researchers developed and applied a model for gravitational settling of microplastic fibers in the atmosphere, examining how fiber shape and size influence atmospheric residence time and deposition patterns to better understand the global atmospheric transport cycle of microplastics.

2022 Digital Commons - USU (Utah State University)
Article Tier 2

Long-distance atmospheric transport of microplastic fibers depends on their shapes

Researchers developed a theory-based settling velocity model for microplastic fibers in the atmosphere that accounts for fiber shape and cross-sectional dimensions, finding that correctly characterising flat fibers rather than treating them as cylinders increases estimated mean atmospheric residence time by over 450%, suggesting the ocean is a major source of airborne plastic and that long-range transport is far more efficient than previously thought.

2023 5 citations
Article Tier 2

Full rotational dynamics of plastic microfibers in turbulence

Researchers conducted Lagrangian experiments on elongated, large aspect-ratio curved plastic microfibers near the Kolmogorov length scale in turbulence, tracking their three-dimensional orientation optically to characterize rotational dynamics and settling behavior that govern microplastic transport and dispersion in the ocean.

2024 arXiv (Cornell University)
Article Tier 2

Atmospheric transport of microplastic particles as a function of their size and shape

Researchers investigated the atmospheric transport and settling of microplastic particles as a function of size and shape, implementing a shape-correction parameterization for fiber-shaped particles in an atmospheric transport model to better represent their reduced gravitational settling velocity compared to spheres. The study showed that non-spherical fibers experience greater atmospheric drag, increasing their residence time and transport distance, and that including shape effects improved agreement between model output and ground-based measurements.

2022
Article Tier 2

Towards realistic predictions of microplastic fiber transport in aquatic environments: Secondary motions

Researchers developed an improved drag model for predicting microplastic fiber settling in water by incorporating secondary motions including tumbling and oscillation in addition to the standard drag forces. Secondary motions profoundly affect settling trajectories and deposited positions, and the new model outperforms existing approaches that neglect these behaviors.

2022 Water Research 50 citations
Article Tier 2

Low Reynolds Number Settling of Bent Rods in Quiescent Fluid

Scientists studied how different shaped fibers (straight vs. bent) fall through water and found that bent fibers settle up to 57% faster than straight ones of the same size. This research helps us better understand how tiny fiber particles like microplastics move through air and water in our environment. The findings could improve predictions of where these particles end up, which matters for tracking pollution that might affect human health.

2026 Fluids
Article Tier 2

Inertial effects on the transport of an anisotropic particle in surface gravity waves

Researchers modeled the transport and rotation of ellipsoidal particles — representing microplastic fibers and other non-spherical shapes — in surface ocean waves. They found that particle shape significantly affects horizontal drift, with elongated particles drifting at different rates than spheres. These results indicate that accurately predicting the transport of fiber microplastics in the ocean requires accounting for particle shape.

2023
Article Tier 2

Transport of anisotropic particles under waves

A computer model showed that non-spherical particles (like many microplastic fragments and fibers) behave differently from spherical ones in wave-driven water flow, affecting how they orient and where they travel. Accounting for particle shape is important for accurately predicting where microplastic debris accumulates in coastal and ocean environments.

2017 Journal of Fluid Mechanics 77 citations
Article Tier 2

Sedimentation and shear-induced dynamics of spheroids in fluids with spatial viscosity variations

Researchers used a generalized reciprocal theorem approach to analytically model how spheroid-shaped particles—relevant to elongated microplastics—settle and rotate in viscosity-stratified fluids. The analysis provides theoretical predictions for how viscosity gradients in natural water columns affect the transport dynamics of non-spherical microplastic particles.

2025 Journal of Fluid Mechanics 2 citations
Article Tier 2

Contextual existence of an optimum through-plane orientation and aspect ratio of a fiber-segment in fibrous air filters

Not relevant to microplastics — this study uses computational fluid dynamics to model how the orientation and shape of fiber segments in air filters affect airborne particle capture efficiency and pressure drop.

2024 Physics of Fluids 3 citations
Article Tier 2

Prediction of the settlement of submillimeter microplastic fibers in still water

Using fluid dynamics simulations validated by experiments, researchers modeled how submillimeter synthetic textile fibers sink through still water, finding that standard drag equations (Stokes law) apply when fibers orient horizontally. They developed an improved drag model that accounts for fiber orientation, enabling more accurate predictions of where microfibers ultimately settle in lakes, rivers, and oceans. Knowing where fibers accumulate helps identify which aquatic habitats and organisms face the greatest exposure.

2024 Environmental Technology & Innovation 3 citations
Article Tier 2

Inertial loads on a finite-length cylinder embedded in a steady uniform flow

Researchers modeled inertial forces acting on a finite-length cylinder embedded in steady uniform flow, contributing to the fluid dynamics understanding relevant to fiber and microplastic transport in aquatic environments. The computational findings improve predictions of how elongated particles move and settle in flowing water.

2023 Physical Review Fluids 7 citations
Article Tier 2

Twist, turn and encounter: the trajectories of small atmospheric particles unravelled

This study used trajectory modeling to trace the movement of small atmospheric particles including microplastics, uncovering complex transport pathways driven by turbulence, wind patterns, and particle size interactions.

2024 arXiv (Cornell University)
Article Tier 2

Shape Matters: Long-Range Transport of Microplastic Fibers in the Atmosphere

Researchers used atmospheric modeling to explain how microplastic fibers can travel long distances through the air, even reaching remote locations far from population centers. They found that the elongated shape of fibers gives them significantly different aerodynamic properties than spherical particles, allowing them to stay airborne much longer. The study helps explain why microplastics have been detected in pristine environments like mountain peaks and polar regions.

2023 Environmental Science & Technology 111 citations
Article Tier 2

Settling velocity of microplastic particles having regular and irregular shapes

Researchers measured how quickly microplastic particles of various shapes settle through water, testing 66 different particle types including spheres, cylinders, fibers, and irregular fragments. They found that particle shape significantly affects settling speed, with fibers and flat shapes sinking more slowly than spheres of the same size. The study provides new equations for predicting where microplastics end up in oceans and waterways based on their shape.

2023 Environmental Research 86 citations