Navier–Stokes and direct Monte-Carlo simulations of the circumnuclear gas coma

Захаров, Владимир; Родионов, А. В.; Lukyanov, G. A.; Crifo, J. F.

doi:10.1016/j.icarus.2007.08.038

Cited by 11 publications

(8 citation statements)

References 19 publications

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“…Crifo et al (2002Crifo et al ( , 2003 also present models with Q within a factor $2 of our 1.3 AU production rate, but only for nuclei that are substantially larger than ours (R nuc = 5.0 km or 24.54 km). Large differences in nucleus size makes meaningful comparisons between models difficult, as illustrated by cross-checking our 2.5 AU model against model ''205" by Zakharov et al (2008a) which has a Q-value only 11% below ours but considers a substantially larger nucleus (R nuc = 6.95 km). In our model, the gas obtains the expansion velocity W = 600 m s À1 at a height of 2 km (where we have n % 3.4 Â 10 15 molec m À3 ), while model 205 reaches the same value at a height of 7 km along the comet-Sun axis (at that point, their n is $5 times smaller than ours).…”

Section: Discussionmentioning

confidence: 98%

“…The models presented by Crifo et al (2002) and Zakharov et al (2008a) all have production rates that are at least an order of magnitude higher. Crifo et al (2003) performed calculations for Q being a factor $3 smaller than ours, but only show the number density within 2 km of the irregularly shaped nucleus, which is substantially smaller (nucleus radius $0.5 km) than in the current study.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Gas kinetics and dust dynamics in low-density comet comae

Davidsson

Gulkis

Alexander

et al. 2010

Icarus

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Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

Gas kinetics and dust dynamics in low-density comet comae

Davidsson

Gulkis

Alexander

et al. 2010

Icarus

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“…In this regard, it may be useful to combine both kinetic and hydrodynamic approaches in the area of their validity to achieve the maximum performance of a numerical model. Some recent developments in coupling of DSMC and computational fluid dynamics approaches are presented by Abbate et al (2009), Burt & Boyd (2009a, 2009b, Holman & Boyd (2009), Roveda et al (1998), Zakharov et al (2008), and Schwartzentruber et al (2008and Schwartzentruber et al ( , 2006. Associated with the coupling, the breakdown parameter is described by Ozawa et al (2010).…”

Section: Modeling Of the Coma Of Comet Churyumov-gerasimenkomentioning

confidence: 99%

Numerical Simulation of Dust in a Cometary Coma: Application to Comet 67p/Churyumov-Gerasimenko

Tenishev

Combi

Rubin

2011

ApJ

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The Rosetta spacecraft is en route to comet 67P/Churyumov-Gerasimenko for a rendezvous, landing, and extensive orbital phase beginning in 2014. With a limited amount of available observational data, planning of the mission as well as the interpretation of measurements obtained by instruments on board the spacecraft requires modeling of the dusty/gas environment of the comet. During the mission, the collision regime in the inner coma will change starting from transitional to fully collisionless. As a result, a physically correct model has to be valid at conditions that are far from equilibrium and account for the kinetic nature of the processes occurring in the coma. A study of the multi-species coma of comet 67P/Churyumov-Gerasimenko is presented in our previous paper, where we describe our kinetic model and discuss the results of its application to cases that correspond to the different stages during the mission. In this work, we focus on numerical modeling of the dust phase in the coma of comet 67P/Churyumov-Gerasimenko and its interaction with the surrounding gas. The basic phenomena that govern the dynamics and energy balance of the dust grains are outlined. The effect of solar radiation pressure and the nucleus gravity in limiting the maximum liftable mass of the grains is discussed. The distribution of the terminal velocity of the dust grains as a function of subsolar angle is derived in the paper. We have found that in the regions with high gradients of the gas density, spike-like features can form in the dust flow. The obtained results represent the state of the coma in the vicinity of the nucleus for a series of stages throughout the Rosetta mission. The implications of the model results for future measurements by the GIADA instrument are discussed.

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“…Since this approach can't be used for the simulation in the Knudsen layer, it is necessary to introduce an additional model which links parameters on the surface and on the top of the Knudsen layer -the initial boundary for the gas dynamics simulations. It was shown that the gas dynamics approach with appropriate boundary conditions can provide a physically adequate description of the gas flow even at a moderate degree of rarefaction, but in this case, it is necessary to verify the adequacy of solutions in each particular case (Crifo et al 2002aLukyanov et al 2005;Zakharov et al 2008). It is important to note the difference between "an adequate description" and "a precise description".…”

Section: Expansion Of the Gasmentioning

confidence: 99%

Cometary Comae-Surface Links

et al. 2020

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A comet is a highly dynamic object, undergoing a permanent state of change. These changes have to be carefully classified and considered according to their intrinsic temporal and spatial scales. The Rosetta mission has, through its contiguous in-situ and remote sensing coverage of comet 67P/Churyumov-Gerasimenko (hereafter 67P) over the time span of August 2014 to September 2016, monitored the emergence, culmination, and winding down of the gas and dust comae. This provided an unprecedented data set and has spurred a large effort to connect in-situ and remote sensing measurements to the surface. In this review, we address our current understanding of cometary activity and the challenges involved when linking comae data to the surface. We give the current state of research by describing what we know about the physical processes involved from the surface to a few tens of kilometres above it with respect to the gas and dust emission from cometary nuclei. Further, we describe how complex multidimensional cometary gas and dust models have developed from the Halley encounter of 1986 to today. This includes the study of inhomogeneous outgassing and determination of the gas and dust production rates. Additionally, the different approaches used and results obtained to link coma data to the surface will be discussed. We discuss forward and inversion models and we describe the limitations of the respective approaches. The current literature suggests that there does not seem to be a single uniform process behind cometary activity. Rather, activity seems to be the consequence of a variety of erosion processes, including the sublimation of both water ice and more volatile material, but possibly also more exotic processes such as fracture and cliff erosion under thermal and mechanical stress, sub-surface heat storage, and a complex interplay of these processes. Seasons and the nucleus shape are key factors for the distribution and temporal evolution of activity and imply that the heliocentric evolution of activity can be highly individual for every comet, and generalisations can be misleading.

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Navier–Stokes and direct Monte-Carlo simulations of the circumnuclear gas coma

Cited by 11 publications

References 19 publications

Gas kinetics and dust dynamics in low-density comet comae

Gas kinetics and dust dynamics in low-density comet comae

Numerical Simulation of Dust in a Cometary Coma: Application to Comet 67p/Churyumov-Gerasimenko

Cometary Comae-Surface Links

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