Recent Progress on Planetary Dust Grain Dynamics

2007 ◽  
Author(s):  
J. E. Howard ◽  
Michail D. Todorov
Keyword(s):  
Recent Progress ◽  
Dust Grain ◽  
Grain Dynamics

scholarly journals Small dust grain dynamics on adaptive mesh refinement grids

2019 ◽  
Vol 626 ◽  
pp. A96 ◽  
Author(s):  
U. Lebreuilly ◽  
B. Commerçon ◽  
G. Laibe
Keyword(s):  
Finite Volume ◽  
Adaptive Mesh Refinement ◽  
Mesh Refinement ◽  
Adaptive Mesh ◽  
Uniform Grids ◽  
Dust Dynamics ◽  
Protostellar Collapse ◽  
Dust Grain ◽  
Grain Dynamics ◽  
Small Dust

Context. Small dust grains are essential ingredients of star, disk and planet formation. Aims. We present an Eulerian numerical approach to study small dust grain dynamics in the context of star and protoplanetary disk formation. It is designed for finite volume codes. We use it to investigate dust dynamics during the protostellar collapse. Methods. We present a method to solve the monofluid equations of gas and dust mixtures with several dust species in the diffusion approximation implemented in the adaptive-mesh-refinement code RAMSES. It uses a finite volume second-order Godunov method with a predictor-corrector MUSCL scheme to estimate the fluxes between the grid cells. Results. We benchmark our method against six distinct tests, DUSTYADVECT, DUSTYDIFFUSE, DUSTYSHOCK, DUSTYWAVE, SETTLING, and DUSTYCOLLAPSE. We show that the scheme is second-order accurate in space on uniform grids and intermediate between second- and first-order on non-uniform grids. We apply our method on various DUSTYCOLLAPSE simulations of 1 M⊙ cores composed of gas and dust. Conclusions. We developed an efficient approach to treat gas and dust dynamics in the diffusion regime on grid-based codes. The canonical tests were successfully passed. In the context of protostellar collapse, we show that dust is less coupled to the gas in the outer regions of the collapse where grains larger than ≃100 μm fall significantly faster than the gas.

On the drag force on non-spherical dust grain

2010 ◽  
Vol 77 (2) ◽  
pp. 271-276 ◽  
Author(s):  
S. I. KRASHENINNIKOV ◽  
D. A. MENDIS
Keyword(s):  
Flow Velocity ◽  
Drag Force ◽  
Plasma Flow ◽  
Dust Grain ◽  
Grain Dynamics

AbstractIt is shown that the direction of the drag force imposed on non-spherical grain by plasma flow is not necessarily aligned with the flow velocity. The implications of this fact for a grain dynamics are discussed.

scholarly journals Dawes Review 7: The Tidal Downsizing Hypothesis of Planet Formation

2017 ◽  
Vol 34 ◽  
Author(s):  
Sergei Nayakshin
Keyword(s):  
Excited State ◽  
Dynamic Systems ◽  
Planet Formation ◽  
Brown Dwarfs ◽  
Population Synthesis ◽  
Open Questions ◽  
New Interpretation ◽  
Dust Grain ◽  
Grain Dynamics ◽  
Massive Cores

AbstractTidal Downsizing scenario of planet formation builds on ideas proposed by Gerard Kuiper in 1951. Detailed simulations of self-gravitating discs, gas fragments, dust grain dynamics, and planet evolutionary calculations are summarised here and used to build a predictive population synthesis. A new interpretation of exoplanetary and debris disc data, the Solar System's origins, and the links between planets and brown dwarfs is offered. Tidal Downsizing predicts that presence of debris discs, sub-Neptune mass planets, planets more massive than ~ 5 Jupiter masses and brown dwarfs should not correlate strongly with the metallicity of the host. For gas giants of ~ Saturn to a few Jupiter mass, a strong host star metallicity correlation is predicted only inwards of a few AU from the host. Composition of massive cores is predicted to be dominated by rock rather than ices. Debris discs made by Tidal Downsizing have an innermost edge larger than about 1 au, have smaller total masses and are usually in a dynamically excited state. Planet formation in surprisingly young or very dynamic systems such as HL Tau and Kepler-444 may be a signature of Tidal Downsizing. Open questions and potential weaknesses of the hypothesis are pointed out.

scholarly journals Dust grain dynamics due to nonuniform and nonstationary high-frequency radiations in cold magnetoplasmas

2006 ◽  
Vol 24 (2) ◽  
pp. 467-474 ◽  
Author(s):  
A. K. Nekrasov ◽  
F. Z. Feygin
Keyword(s):  
Electric Fields ◽  
High Frequency ◽  
Electromagnetic Waves ◽  
Low Frequency ◽  
Plasma Parameters ◽  
Laboratory Plasmas ◽  
Background Magnetic Field ◽  
Spatio Temporal ◽  
Dust Grain ◽  
Grain Dynamics

Abstract. A general nonlinear theory for low-frequency electromagnetic field generation due to high-frequency nonuniform and nonstationary electromagnetic radiations in cold, uniform, multicomponent, dusty magnetoplasmas is developed. This theory permits us to consider the nonlinear action of all waves that can exist in such plasmas. The equations are derived for the dust grain velocities in the low-frequency nonlinear electric fields arising due to the presence of electromagnetic cyclotron waves travelling along the background magnetic field. The dust grains are considered to be magnetized as well as unmagnetized. Different regimes for the dust particle dynamics, depending on the spatio-temporal change of the wave amplitudes and plasma parameters, are discussed. It is shown that induced nonlinear electric fields can have both an electrostatic and electromagnetic nature. Conditions for maximum dust acceleration are found. The results obtained may be useful for understanding the possible mechanisms of dust grain dynamics in astrophysical, cosmic and laboratory plasmas under the action of nonuniform and nonstationary electromagnetic waves.

Electron-Mirror Microscopic Aspects of Ferroelectric Domains of BaTiO3 And Ca2Sr (C2H5CO2)6

1970 ◽  
Vol 28 ◽  
pp. 478-479
Author(s):  
Teruo Someya ◽  
Jinzo Kobayashi
Keyword(s):  
Surface Layer ◽  
Electric Fields ◽  
Quantitative Study ◽  
Recent Progress ◽  
Ferroelectric Domain ◽  
Resolving Power ◽  
Surface Pattern ◽  
Crystal Surfaces ◽  
One Dimensional ◽  
Ferroelectric Domains

Recent progress in the electron-mirror microscopy (EMM), e.g., an improvement of its resolving power together with an increase of the magnification makes it useful for investigating the ferroelectric domain physics. English has recently observed the domain texture in the surface layer of BaTiO3. The present authors ) have developed a theory by which one can evaluate small one-dimensional electric fields and/or topographic step heights in the crystal surfaces from their EMM pictures. This theory was applied to a quantitative study of the surface pattern of BaTiO3).

The Nature of Oxide Surfaces: Topographic and Electronic Structure

1993 ◽  
Vol 51 ◽  
pp. 966-967
Author(s):  
Dawn A. Bonnell ◽  
Yong Liang
Keyword(s):  
Transition Metal Oxides ◽  
Electronic Structures ◽  
Recent Progress ◽  
Spatial Localization ◽  
Level Of Detail ◽  
Scanning Tunneling ◽  
Oxide Surfaces ◽  
Tunneling Microscopy ◽  
Considerable Effort ◽  
Complete Understanding

Recent progress in the application of scanning tunneling microscopy (STM) and tunneling spectroscopy (STS) to oxide surfaces has allowed issues of image formation mechanism and spatial resolution limitations to be addressed. As the STM analyses of oxide surfaces continues, it is becoming clear that the geometric and electronic structures of these surfaces are intrinsically complex. Since STM requires conductivity, the oxides in question are transition metal oxides that accommodate aliovalent dopants or nonstoichiometry to produce mobile carriers. To date, considerable effort has been directed toward probing the structures and reactivities of ZnO polar and nonpolar surfaces, TiO2 (110) and (001) surfaces and the SrTiO3 (001) surface, with a view towards integrating these results with the vast amount of previous surface analysis (LEED and photoemission) to build a more complete understanding of these surfaces. However, the spatial localization of the STM/STS provides a level of detail that leads to conclusions somewhat different from those made earlier.

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