Dataset Information

Advantages of a conservative velocity interpolation (CVI) scheme for particle-in-cell methods with application in geodynamic modeling.

ABSTRACT: The particle-in-cell method is generally considered a flexible and robust method to model the geodynamic problems with chemical heterogeneity. However, velocity interpolation from grid points to particle locations is often performed without considering the divergence of the velocity field, which can lead to significant particle dispersion or clustering if those particles move through regions of strong velocity gradients. This may ultimately result in cells void of particles, which, if left untreated, may, in turn, lead to numerical inaccuracies. Here we apply a two-dimensional conservative velocity interpolation (CVI) scheme to steady state and time-dependent flow fields with strong velocity gradients (e.g., due to large local viscosity variation) and derive and apply the three-dimensional equivalent. We show that the introduction of CVI significantly reduces the dispersion and clustering of particles in both steady state and time-dependent flow problems and maintains a locally steady number of particles, without the need for ad hoc remedies such as very high initial particle densities or reseeding during the calculation. We illustrate that this method provides a significant improvement to particle distributions in common geodynamic modeling problems such as subduction zones or lithosphere-asthenosphere boundary dynamics.

SUBMITTER: Wang H

PROVIDER: S-EPMC5089062 | biostudies-literature | 2015 Jun

REPOSITORIES: biostudies-literature

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Advantages of a conservative velocity interpolation (CVI) scheme for particle-in-cell methods with application in geodynamic modeling.

Wang Hongliang H Agrusta Roberto R van Hunen Jeroen J

Geochemistry, geophysics, geosystems : G(3) 20150612 6

The particle-in-cell method is generally considered a flexible and robust method to model the geodynamic problems with chemical heterogeneity. However, velocity interpolation from grid points to particle locations is often performed without considering the divergence of the velocity field, which can lead to significant particle dispersion or clustering if those particles move through regions of strong velocity gradients. This may ultimately result in cells void of particles, which, if left untre ...[more]

PMID: 27840594

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Project description:To examine whether the actual dimensions of human facial features are important to the development of a low-velocity inhalable particulate mass sampling criterion, this study evaluated the effect of facial feature dimensions (nose and lips) on estimates of aspiration efficiency of inhalable particles using computational fluid dynamics modeling over a range of indoor air and breathing velocities. Fluid flow and particle transport around four humanoid forms with different facial feature dimensions were simulated. All forms were facing the wind (0.2, 0.4 m s(-1)), and breathing was simulated with constant inhalation (1.81, 4.3, 12.11 m s(-1)). The fluid flow field was solved using standard k-epsilon turbulence equations, and laminar particle trajectories were used to determine critical areas defining inhaled particles. The critical areas were then used to compute the aspiration efficiency of the mouth-breathing humanoid. One-tailed t-tests indicated that models with larger nose and lip features resulted in significantly lower aspiration efficiencies than geometries with smaller features, but the shape of the orifice into the mouth (rounded rectangle versus elliptical) had no effect on aspiration efficiency. While statistically significant, the magnitudes of differences were small: on average, the large nose reduced aspiration efficiency by 6.5% and the large lips reduced aspiration efficiency by 3.2%. In comparison, a change in breathing velocity from at-rest to heavy increased aspiration efficiency by an average of 21% over all particle sizes, indicating a much greater impact of aspiration efficiency on breathing rate in the facing-the-wind orientation. Linear regression models confirmed that particle diameter and breathing velocity were significant predictors to the aspiration fraction, while the facial feature dimensions were not significant contributors to a unifying model. While these effects may be less pronounced as the orientation changes from facing-the-wind, their impact confirms the importance of breathing velocity and, to a lesser extent, facial feature dimensions on exposure estimates in low freestream velocities typical of occupational environments.

Dataset Information

Advantages of a conservative velocity interpolation (CVI) scheme for particle-in-cell methods with application in geodynamic modeling.

Publications

Advantages of a conservative velocity interpolation (CVI) scheme for particle-in-cell methods with application in geodynamic modeling.

Similar Datasets

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