Papers

61,005 results
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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
Article Tier 2

Modeling the settling and resuspension of microplastics in rivers: Effect of particle properties and flow conditions

Researchers developed a mathematical model to simulate how microplastics of different shapes settle and resuspend in rivers, moving beyond the common assumption that all particles are spherical. They found that turbulence has a complex effect, sometimes keeping particles suspended longer and sometimes accelerating their settling, depending on flow conditions. The model reveals that particle shape significantly influences where microplastics end up in river systems.

2024 Water Research 36 citations
Article Tier 2

A settling velocity formula for irregular shaped microplastic fragments based on new shape factor: Influence of secondary motions

Researchers developed a new shape factor for irregular microplastic fragments and derived a settling velocity formula based on it, using numerical modeling to show that fragment shape governs whether particles sink stably or oscillate — providing more accurate predictions of microplastic transport in rivers and lakes than existing methods.

2024 The Science of The Total Environment 7 citations
Article Tier 2

Settling behaviour of irregular-shaped polystyrene microplastics

Researchers studied the settling behavior of irregular-shaped polystyrene microplastics in water, finding that shape significantly affects how fast particles sink. Understanding settling behavior is important for predicting how microplastics distribute vertically in rivers and ocean water columns.

2021 Science & Technology Development Journal - Engineering and Technology 7 citations
Article Tier 2

Response of microplastic particles to turbulent flow: An experimental study

Using controlled flume experiments, researchers studied how turbulent flow conditions affect the transport and settling behavior of microplastic particles with varied shapes and densities, finding that turbulence intensity and particle morphology interacted to determine suspension and deposition patterns.

2025
Article Tier 2

Settling velocity of microplastic particles of regular shapes

This study measured the sinking velocities of spherical, cylindrical, and filament-shaped microplastic particles ranging from 0.5 to 5 mm, finding that shape strongly determines how quickly particles settle through the water column. Understanding settling behavior is essential for modeling how microplastics are transported and deposited in marine environments.

2016 Marine Pollution Bulletin 457 citations
Article Tier 2

Empirical Shape-Based Estimation of Settling Microplastic Particles Drag Coefficient

This study experimentally measured the settling behavior of flat square microplastic particles in water, finding that shape significantly affects sinking speed and drag compared to spherical particles. Understanding how microplastic shapes influence settling is essential for modeling where plastics accumulate in rivers and ocean sediments.

2023 Journal of Marine Science and Engineering 2 citations
Article Tier 2

Settling of inertial nonspherical particles in wavy flow

Lab experiments showed that plastic particles of different shapes — rods, disks, and spheres — settle at different rates in wavy water, and waves can both speed up and slow down their sinking. Understanding how particle shape affects transport in ocean currents is key to predicting where microplastics accumulate.

2020 Physical Review Fluids 21 citations
Article Tier 2

On the vertical structure of non-buoyant plastics in turbulent transport

Researchers investigated how non-floating plastic debris moves through river-like flows and found that plastics settle in unique, complex patterns due to their irregular shapes. In low-turbulence conditions, interactions between the plastic particles and the riverbed enhanced mixing beyond what standard sediment transport models would predict. The study proposes a new equation for describing how plastics are distributed vertically in flowing water.

2024 Water Research 22 citations
Article Tier 2

Settling velocities of microplastics with different shapes in sediment-water mixtures

Researchers studied how the shape of microplastic particles affects how quickly they sink in water containing suspended sediment. They found that fibers and films settle much more slowly than fragments and pellets, and that sediment in the water significantly slows the settling of all microplastic types. These findings are important for predicting where microplastics accumulate in lakes, rivers, and oceans.

2025 Environmental Pollution 14 citations
Article Tier 2

Settling behaviors of microplastic disks in acceleration fall

Researchers studied the settling behavior of disk-shaped microplastics during free-fall in water, using high-speed imaging to track the orientation and velocity of particles as they descended. Disk-shaped particles exhibited oscillating and tumbling motions that slowed settling compared to spheres of equivalent mass, with implications for predicting microplastic transport and deposition in aquatic environments.

2024 Marine Pollution Bulletin 6 citations
Article Tier 2

Towards better predicting the settling velocity of film-shaped microplastics based on experiment and simulation data

Researchers combined experimental and simulation data to better predict how film-shaped microplastics settle through water, since most existing models are based on spherical particles. They found that the particle definition approach was more suitable than equivalent spherical diameter for characterizing flat, irregular microplastics. The improved settling velocity predictions could help scientists better understand how film-shaped microplastics travel and accumulate in aquatic environments.

2024 Marine Pollution Bulletin 10 citations
Article Tier 2

Settling velocity of microplastics in turbulent open-channel flow

Researchers studied how microplastic particles settle in turbulent river-like flow conditions compared to still water and developed a new formula to predict their behavior. They found that turbulence altered settling velocities by as much as 26% depending on particle properties, with larger, heavier particles being less influenced by water turbulence. The findings are important for building better models of how microplastics are transported and distributed in rivers and other flowing waterways.

2024 The Science of The Total Environment 22 citations
Article Tier 2

Mobility and retention of microplastic fibers and irregular plastic fragments in fluvial systems: an experimental flume study

Researchers conducted experimental flume studies to compare the mobility and retention of microplastic fibres and irregularly shaped plastic fragments in fluvial systems. The study found that particle shape strongly influences transport behaviour, with fibres exhibiting greater mobility and distinct retention patterns compared to irregular fragments, highlighting the need to move beyond spherical particle models in microplastic transport research.

2025 Microplastics and Nanoplastics
Article Tier 2

Modeling Microplastic Transport in the Marine Environment: Testing Empirical Models of Particle Terminal Sinking Velocity for Irregularly Shaped Particles

Researchers tested multiple drag models for predicting the terminal settling velocity of irregularly shaped microplastic particles in seawater, identifying three high-precision models and demonstrating that settling velocity is largely stable across ocean depths and independent of initial particle velocity, improving the accuracy of marine microplastic transport simulations.

2023 ACS ES&T Water 12 citations
Article Tier 2

Sinking velocity of sub-millimeter microplastic

Researchers measured the sinking velocities of irregularly shaped microplastic particles (polyamide, PMMA, and PET, 6–251 μm) and found they sink considerably slower than theoretical predictions for spheres of equivalent size, developing a predictive model based on particle size and excess density to better represent how real-world microplastics settle through the water column.

2018 Marine Pollution Bulletin 109 citations
Article Tier 2

Plastic drift : Mapping the course of microplastic transport in turbulent riverine flows.

Researchers investigated the transport dynamics of 24 negatively buoyant microplastic particles across a spectrum of sizes, shapes, and densities using a 3D particle tracking system in turbulent open channel flow, generating 720 trajectories. They found that particle shape was the dominant determinant of transport behavior, with fibers tending to remain near the water surface at lower forward velocities while spheres stayed closer to the bed with higher forward velocities.

2024 Zenodo (CERN European Organization for Nuclear Research)
Article Tier 2

Effect of Shape and Size on the Transport of Floating Particles on the Free Surface in a Natural Stream

Researchers used particle tracking velocimetry to study how shape and size affect the movement of floating particles on the turbulent free surface of a natural stream, finding that millimeter-scale spheres behaved differently from centimeter-scale irregular objects. Understanding particle transport mechanics is essential for predicting microplastic fate in river systems.

2023 Water Resources Research 17 citations
Article Tier 2

Settling of nonuniform cylinders at intermediate Reynolds numbers

This study investigated the settling behavior of non-uniform cylindrical particles at intermediate Reynolds numbers, providing new data on how particle shape and aspect ratio influence drag and settling velocity. The findings are relevant to predicting the transport and deposition of microplastic fibers in water.

2024 Physical Review Fluids 7 citations
Article Tier 2

Improved Settling Velocity for Microplastic Fibers: A New Shape-Dependent Drag Model

A new shape-dependent drag model was developed to improve the accuracy of settling velocity predictions for microplastic fibers, addressing a major limitation of existing drag models that significantly underpredict fiber settling in aquatic environments.

2021 Environmental Science & Technology 85 citations
Article Tier 2

Coupled CFD-DEM modelling to assess settlement velocity and drag coefficient of microplastics

Researchers used computational fluid dynamics coupled with particle simulations to model how the size, shape, and density of microplastics affect their settling velocity and drag in water. Accurate physical models of microplastic behavior are essential for predicting where particles accumulate in rivers, lakes, and the ocean.

2020 1 citations
Article Tier 2

Entrainment and vertical mixing of aquatic microplastics in turbulent flow: The coupled role of particle size and density

Researchers conducted laboratory flume experiments to study how turbulence affects the vertical mixing and entrainment of microplastic particles of different sizes and densities. Both particle size and polymer density significantly influenced mixing behavior, with smaller and denser particles more responsive to turbulent structures, informing models of microplastic transport in rivers and coastal waters.

2022 Marine Pollution Bulletin 50 citations
Article Tier 2

Effects of Particle Properties on the Settling and Rise Velocities of Microplastics in Freshwater under Laboratory Conditions

Physical experiments quantified the settling and rise velocities of ~500 microplastic particles of varying shapes, sizes, and densities under controlled laboratory conditions, finding velocities ranging from 0.39 cm/s (settling polyamide fibers) to 31.4 cm/s (rising expanded polystyrene), with standard sediment transport formulas inadequate for fibers. The study provides empirical data needed to improve models of microplastic transport in rivers and lakes.

2019 Environmental Science & Technology 425 citations
Article Tier 2

Analysis of hydraulic conditions considering the influence of particle shape

This review article examined how particle shape influences fluid dynamics and sediment transport across various engineering and environmental contexts. Understanding particle shape effects is relevant to predicting how microplastics of different shapes move and settle in aquatic environments.

2023 International Journal of Hydropower and Civil Engineering