Electrical properties of eolian sand and silt

Kanagy, Sherman P.; Mann, C. John

doi:10.1016/0012-8252(94)90057-4

Cited by 27 publications

(14 citation statements)

References 77 publications

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“…Then, the calculated electric fields are compared with the experimental data measured by Schmidt et al [1998] to verify the theoretical model and the algorithm suggested in this paper. Since the saltating particles are usually presumed to be negatively charged [ Latham , 1964; Greeley and Leach , 1978; Israelsson , 1994; Kanagy and Mann , 1994; Horányi and Lawrence , 2001; Zheng et al , 2003], their average charge‐to‐mass ratio is taken as c = −60 μC kg −1 , which is equal in magnitude to that measured at 5 cm height above the bed by Schmidt et al [1998]. When the wind velocity is 12 m s −1 at 1.5 m height above the bed, the electric field intensity calculated at 1.7 cm height is 168 kV m −1 , which is very close to the value of 166 kV m −1 measured at the same height by Schmidt et al [1998].…”

Section: Numerical Results and Discussionmentioning

confidence: 99%

“…Among various phenomena accompanying the windblown sand flux, more attention is increasingly being paid to the electrification of the sand particles and the electric field produced by these charged particles [ Freier , 1960; Mills , 1977; Israelsson , 1994; Kanagy and Mann , 1994; Horányi and Lawrence , 2001]. The electric field will produce pronounced interference with radio communication, and it might affect the accuracy of instruments used on the surface of planets such as Mars or Saturn [ Greeley and Leach , 1978; White et al , 1997; Sickafoose et al , 2001].…”

Section: Introductionmentioning

confidence: 99%

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Theoretical model of the electric field produced by charged particles in windblown sand flux

Zheng

Zhou

2004

J. Geophys. Res.

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[1] Taking into account the coupled interactions among wind velocity, sand movement, and the electric field, we develop a general theoretical model for calculating the electric fields produced by charged sand particles in the three sand movement types, saltation, suspension and creep, quantifying the electric field of a point charge by Coulomb's law. The numerical results of the electric field are in good agreement with both the field data and the wind tunnel experimental results. The profile of the electric field intensity produced by charged particles in windblown sand flux is quantitatively analyzed in detail and compared with those generated by charged particles only in the saltation layer or in the creep layer. The results demonstrate that the profile of the electric field produced by charged particles in one sand movement type is different from that by those in other types and that the signs of the charge acquired by the particles also alter the features of the profile. Finally, the effects of the wind velocity and the charge of the windblown sand particles on the electric field intensity are discussed.

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Section: Numerical Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Theoretical model of the electric field produced by charged particles in windblown sand flux

Zheng

Zhou

2004

J. Geophys. Res.

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“…Wet rock specimens were fractured and a transient SP spike was observed near the time of failure that may be caused by contact electrification (or separation electrification). In this phenomenon, oppositely charged crack wall surfaces are created as materials rip apart [ Ogawa et al , 1985; Enomoto and Hashimoto , 1990; Horn and Smith , 1992; Kanagy and Mann , 1994]. Electrons migrate to surfaces during contact or separation based on the work function of each surface.…”

Section: Discussionmentioning

confidence: 99%

Self‐potential observations during hydraulic fracturing

Moore¹,

Glaser²

2007

J. Geophys. Res.

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[1] The self-potential (SP) response during hydraulic fracturing of intact Sierra granite was investigated in the laboratory. Excellent correlation of pressure drop and SP suggests that the SP response is created primarily by electrokinetic coupling. For low pressures, the variation of SP with pressure drop is linear, indicating a constant coupling coefficient (Cc) of À200 mV/MPa. However, for pressure drops >2 MPa, the magnitude of the Cc increases by 80% in an exponential trend. This increasing Cc is related to increasing permeability at high pore pressures caused by dilatancy of microcracks and is explained by a decrease in the hydraulic tortuosity. Resistivity measurements reveal a decrease of 2% prior to hydraulic fracturing and a decrease of $35% after fracturing. An asymmetric spatial SP response created by injectate diffusion into dilatant zones is observed prior to hydraulic fracturing, and in most cases this SP variation revealed the impending crack geometry seconds before failure. At rupture, injectate rushes into the new fracture area where the zeta potential is different than in the rock porosity, and an anomalous SP spike is observed. After fracturing, the spatial SP distribution reveals the direction of fracture propagation. Finally, during tensile cracking in a point load device with no water flow, a SP spike is observed that is caused by contact electrification. However, the time constant of this event is much less than that for transients observed during hydraulic fracturing, suggesting that SP created solely from material fracture does not contribute to the SP response during hydraulic fracturing.

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“…The Earth's surface is generally a good conductor because soil particles are usually covered by a thin, conducting film of water [Kanagy and Mann, 1994]. Therefore, the electric field E 0 induces charges at the surface [Wahlin, 1986].…”

Section: Theory Of Dust Lifting By Electric Forcesmentioning

confidence: 99%

Enhancement of the emission of mineral dust aerosols by electric forces

Kok

Rennó

2006

Geophysical Research Letters

106

112

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Climate forcing by mineral dust aerosols is one of the most uncertain processes in our current understanding of climate change. The main natural sources of dust aerosols are blowing dust, dust devils, and dust storms. Electric fields larger than 100 kV/m have been measured in these phenomena. Theoretical calculations and laboratory experiments show that these electric fields produce electric forces that can reduce the critical wind speed necessary to initiate dust lifting and can even directly lift mineral particles from the surface. Thus, we conclude that electric forces enhance the natural lifting of mineral dust aerosols.

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Electrical properties of eolian sand and silt

Cited by 27 publications

References 77 publications

Theoretical model of the electric field produced by charged particles in windblown sand flux

Theoretical model of the electric field produced by charged particles in windblown sand flux

Self‐potential observations during hydraulic fracturing

Enhancement of the emission of mineral dust aerosols by electric forces

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