Drag on Nonspherical Objects

Leith, David

doi:10.1080/02786828708959128

Cited by 187 publications

(136 citation statements)

References 14 publications

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“…where λ is the mean free path of the gas molecules and When χ is known (or estimated), the correlation of Leith (1987) is used to relate χ , D se , and D ve :…”

Section: Accounting For Dust Non-sphericitymentioning

confidence: 99%

Measurements of cloud condensation nuclei activity and droplet activation kinetics of fresh unprocessed regional dust samples and minerals

2011

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Abstract. This study reports laboratory measurements of cloud condensation nuclei (CCN) activity and droplet activation kinetics of aerosols dry generated from clays, calcite, quartz, and desert soil samples from Northern Africa, East Asia/China, and Northern America. Based on the observed dependence of critical supersaturation, s c , with particle dry diameter, D dry , we found that FHH (Frenkel, Halsey and Hill) adsorption activation theory is a far more suitable framework for describing fresh dust CCN activity than Köhler theory. One set of FHH parameters (A FHH ∼ 2.25 ± 0.75, B FHH ∼ 1.20 ± 0.10) can adequately reproduce the measured CCN activity for all species considered, and also explains the large range of hygroscopicities reported in the literature. Based on a threshold droplet growth analysis, mineral dust aerosols were found to display retarded activation kinetics compared to ammonium sulfate. Comprehensive simulations of mineral dust activation and growth in the CCN instrument suggest that this retardation is equivalent to a reduction of the water vapor uptake coefficient (relative to that for calibration ammonium sulfate aerosol) by 30-80%. These results suggest that dust particles do not require deliquescent material to act as CCN in the atmosphere.

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“…where λ is the mean free path of the gas molecules and When χ is known (or estimated), the correlation of Leith (1987) is used to relate χ , D se , and D ve :…”

Section: Accounting For Dust Non-sphericitymentioning

confidence: 99%

Measurements of cloud condensation nuclei activity and droplet activation kinetics of fresh unprocessed regional dust samples and minerals

2011

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“…[23][24][25] A detailed drag force expression proposed by Leith 25 for nonspherical shape particles is used to estimate the drag force on the chain-like magnetic nanoparticle agglomerate (F d,c ),…”

Section: Resultsmentioning

confidence: 99%

Transport characteristics of nanoparticle-based ferrofluids in a gel model of the brain

Basak

Brogan²,

Dietrich³

et al. 2009

IJN

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A current advance in nanotechnology is the selective targeting of therapeutics by external magnetic fi eld-guided delivery. This is an important area of research in medicine. The use of magnetic forces results in the formation of agglomerated structures in the fi eld region. The transport characteristics of these agglomerated structures are explored. A nonintrusive method based on in situ light-scattering techniques is used to characterize the velocity of such particles in a magnetic fi eld gradient. A transport model for the chain-like agglomerates is developed based on these experimental observations. The transport characteristics of magnetic nanoparticle drug carriers are then explored in gel-based simulated models of the brain. Results of such measurements demonstrate decreased diffusion of magnetic nanoparticles when placed in a high magnetic fi eld gradient.

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“…Only the most basic shapes are given in Table 1; many more are given by Davies (1979) and Hinds (1982). In addition, procedures exist for calculating S d for a given geometric shape (Leith 1987) and for agglomerates (Tohno and Takahashi 1990).…”

Section: Discussionmentioning

confidence: 99%

Passive Aerosol Sampler. Part I: Principle of Operation

Wagner¹,

Leith²

2001

Aerosol Science and Technology

Self Cite

102

106

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A method has been developed to estimate average concentrations and size distributions with a miniature passive aerosol sampler. To use the passive sampler, one exposes it to an environment for a period of hours to weeks. The passive sampler is intended to monitor ambient, indoor, or occupational aerosols and has potential utility as a personal sampler. The sampler is inexpensive and easy to operate and is capable of taking long-term samples to investigate chronic exposures. After sampling, the passive sampler is covered and brought to the lab. Scanning electron microscopy (SEM) and automated image analysis are used to count and size collected particles with d p > 0.1 ¹m. Alternatively, more advanced microscopy techniques can be used for ambient-pressure analysis or elemental characterization. Image analysis is used in conjunction with particle density and shape factors to obtain the mass ux as a function of aerodynamic diameter.

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Drag on Nonspherical Objects

Cited by 187 publications

References 14 publications

Measurements of cloud condensation nuclei activity and droplet activation kinetics of fresh unprocessed regional dust samples and minerals

Measurements of cloud condensation nuclei activity and droplet activation kinetics of fresh unprocessed regional dust samples and minerals

Transport characteristics of nanoparticle-based ferrofluids in a gel model of the brain

Passive Aerosol Sampler. Part I: Principle of Operation

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