Viscosity Measurements on Water Vapor and Their Evaluation

Teske, Viola; Vogel, E.; Bich, Eckard

doi:10.1021/je050288d

Cited by 34 publications

(41 citation statements)

References 27 publications

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“…Our H 2 O profiles agree less, and our OH slopes, the least, due mainly to the strong effect that neutral collisions have on those more polar molecules. In particular, C10 used a much larger cross section for neutral collisions involving H 2 O and OH [Teske et al, 2005] than for atomic oxygen [Bondi, 1964]. This helps to further explain our agreement with their oxygen profile since we exclude neutral-neutral collisions from our model altogether.…”

Section: Discussionmentioning

confidence: 99%

The roles of charge exchange and dissociation in spreading Saturn's neutral clouds

et al. 2012

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[1] Neutrals sourced directly from Enceladus's plumes are initially confined to a dense neutral torus in Enceladus's orbit around Saturn. This neutral torus is redistributed by charge exchange, impact/photodissociation, and neutral-neutral collisions to produce Saturn's neutral clouds. Here we consider the former processes in greater detail than in previous studies. In the case of dissociation, models have assumed that OH is produced with a single speed of 1 km s À1, whereas laboratory measurements suggest a range of speeds between 1 and 1.6 km s À1. We show that the high-speed case increases dissociation's range of influence from 9 to 15 R S . For charge exchange, we present a new modeling approach, where the ions are followed within a neutral background, whereas neutral cloud models are conventionally constructed from the neutrals' point of view. This approach allows us to comment on the significance of the ions' gyrophase at the moment charge exchange occurs. Accounting for gyrophase (1) has no consequence on the H 2 O cloud, (2) doubles the local density of OH at the orbit of Enceladus, and (3) decreases the oxygen densities at Enceladus's orbit by less than 10%. Finally, we consider velocity-dependent, as well as species-dependent cross sections and find that the oxygen cloud produced from charge exchange is spread out more than H 2 O, whereas the OH cloud is the most confined.

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Section: Discussionmentioning

confidence: 99%

The roles of charge exchange and dissociation in spreading Saturn's neutral clouds

et al. 2012

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“…To the database, we added several data sets [30][31][32][33][34][35][36] published after the compilation of Ref. 29.…”

Section: Experimental Datamentioning

confidence: 99%

New International Formulation for the Viscosity of H2O

Huber¹,

Perkins²,

Laesecke³

et al. 2009

Journal of Physical and Chemical Reference Data

374

281

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The International Association for the Properties of Water and Steam (IAPWS) encouraged an extensive research effort to update the IAPS Formulation 1985 for the Viscosity of Ordinary Water Substance, leading to the adoption of a Release on the IAPWS Formulation 2008 for the Viscosity of Ordinary Water Substance. This manuscript describes the development and evaluation of the 2008 formulation, which provides a correlating equation for the viscosity of water for fluid states up to 1173K and 1000MPa with uncertainties from less than 1% to 7% depending on the state point.

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“…which for water at 180 K gives σ 54Å 2 . For a more accurate value, appropriate for use in our calculations involving viscous spreading, we employ the results of Teske et al (2005), who measured experimentally the viscosity of water vapor at temperatures 300-450K and a range of densities. We use the standard relation for kinematic viscosity ν,…”

Section: Processmentioning

confidence: 99%

Saturn in hot water: Viscous evolution of the Enceladus torus

Farmer

2009

Icarus

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The detection of outgassing water vapor from Enceladus is one of the great breakthroughs of the Cassini mission. The fate of this water once ionized has been widely studied; here we investigate the effects of purely neutral-neutral interactions within the Enceladus torus. We find that, thanks in part to the polar nature of the water molecule, a cold (∼ 180 K) neutral torus would undergo rapid viscous heating and spread to the extent of the observed hydroxyl cloud, before plasma effects become important. We investigate the physics behind the spreading of the torus, paying particular attention to the competition between heating and rotational line cooling. A steady-state torus model is constructed, and it is demonstrated that the torus will be observable in the millimeter band with the upcoming Herschel satellite. The relative strength of rotational lines could be used to distinguish between physical models for the neutral cloud.

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Viscosity Measurements on Water Vapor and Their Evaluation

Cited by 34 publications

References 27 publications

The roles of charge exchange and dissociation in spreading Saturn's neutral clouds

The roles of charge exchange and dissociation in spreading Saturn's neutral clouds

New International Formulation for the Viscosity of H2O

Saturn in hot water: Viscous evolution of the Enceladus torus

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