scholarly journals Building Planets with Dusty Gas

2004 ◽  
Vol 213 ◽  
pp. 231-234
Author(s):  
S. T. Maddison ◽  
R. J. Humble ◽  
J. R. Murray
Keyword(s):  
Solar Nebula ◽  
Numerical Technique ◽  
Dynamical Evolution ◽  
Gas Flows ◽  
Dusty Gas ◽  
Dust Distribution ◽  
Self Gravity ◽  
Gas Medium

We have developed a new numerical technique for simulating dusty-gas flows. Our code incorporates gas hydrodynamics, self-gravity and dust drag to follow the dynamical evolution of a dusty-gas medium. We have incorporated several descriptions for the drag between gas and dust phases and can model flows with submillimetre, centimetre and metre size “dust”. We present calculations run on the APAC1 supercomputer following the evolution of the dust distribution in the pre-solar nebula.

Modeling of dusty gas flows due to plume impingement on a lunar surface

2021 ◽  
Vol 33 (5) ◽  
pp. 053307
Author(s):  
Arun K. Chinnappan ◽  
Rakesh Kumar ◽  
Vaibhav K. Arghode
Keyword(s):  
Lunar Surface ◽  
Gas Flows ◽  
Dusty Gas

scholarly journals Growth after the streaming instability

2019 ◽  
Vol 624 ◽  
pp. A114 ◽  
Author(s):  
Beibei Liu ◽  
Chris W. Ormel ◽  
Anders Johansen
Keyword(s):  
Dynamical Evolution ◽  
Bimodal Distribution ◽  
Stokes Number ◽  
Volume Density ◽  
Mass Star ◽  
Type I ◽  
Solar Mass ◽  
Streaming Instability ◽  
Two Component ◽  
Self Gravity

Context. Streaming instability is a key mechanism in planet formation, clustering pebbles into planetesimals with the help of self-gravity. It is triggered at a particular disk location where the local volume density of solids exceeds that of the gas. After their formation, planetesimals can grow into protoplanets by feeding from other planetesimals in the birth ring as well as by accreting inwardly drifting pebbles from the outer disk. Aims. We aim to investigate the growth of planetesimals into protoplanets at a single location through streaming instability. For a solar-mass star, we test the conditions under which super-Earths are able to form within the lifetime of the gaseous disk. Methods. We modified the Mercury N-body code to trace the growth and dynamical evolution of a swarm of planetesimals at a distance of 2.7 AU from the star. The code simulates gravitational interactions and collisions among planetesimals, gas drag, type I torque, and pebble accretion. Three distributions of planetesimal sizes were investigated: (i) a mono-dispersed population of 400 km radius planetesimals, (ii) a poly-dispersed population of planetesimals from 200 km up to 1000 km, (iii) a bimodal distribution with a single runaway body and a swarm of smaller, 100 km size planetesimals. Results. The mono-dispersed population of 400 km size planetesimals cannot form protoplanets of a mass greater than that of the Earth. Their eccentricities and inclinations are quickly excited, which suppresses both planetesimal accretion and pebble accretion. Planets can form from the poly-dispersed and bimodal distributions. In these circumstances, it is the two-component nature that damps the random velocity of the large embryo through the dynamical friction of small planetesimals, allowing the embryo to accrete pebbles efficiently when it approaches 10−2 M⊕. Accounting for migration, close-in super-Earth planets form. Super-Earth planets are likely to form when the pebble mass flux is higher, the disk turbulence is lower, or the Stokes number of the pebbles is higher. Conclusions. For the single site planetesimal formation scenario, a two-component mass distribution with a large embryo and small planetesimals promotes planet growth, first by planetesimal accretion and then by pebble accretion of the most massive protoplanet. Planetesimal formation at single locations such as ice lines naturally leads to super-Earth planets by the combined mechanisms of planetesimal accretion and pebble accretion.

scholarly journals Status of Molecular Opacities of Interest in the Modeling of a Proto-Solar Nebula

1974 ◽  
Vol 65 ◽  
pp. 13-20
Author(s):  
W. F. Huebner ◽  
L. W. Fullerton
Keyword(s):  
Optical Properties ◽  
Equation Of State ◽  
Volatile Compounds ◽  
Gaseous Phase ◽  
Input Data ◽  
Solar Nebula ◽  
Ionic Species ◽  
Constitutive Properties ◽  
Gas Medium ◽  
Basic Input

The report centers on general procedures applicable to the calculation of constitutive properties (equation of state and opacity) of media that serve as models for the solar nebula during planet formation and for the atmospheres of some planets. Specifically considered are the equilibrium compositions of a mixture of atoms, molecules, and their ionic species in the gaseous phase, condensation into grains with refractory cores and mantles of volatile compounds, and the ‘optical’ properties of the grain-gas medium. A summary of available and still needed basic (input) data and some currently available results are presented.

scholarly journals Orbital features of distant trans-Neptunian objects induced by giant gaseous clumps

2020 ◽  
Vol 642 ◽  
pp. L20
Author(s):  
V. V. Emel’yanenko
Keyword(s):  
Simple Model ◽  
Solar Nebula ◽  
Dynamical Evolution ◽  
Outer Solar System ◽  
The Sun ◽  
High Eccentricity ◽  
Small Bodies ◽  
Dynamical Characteristics ◽  
Gravitational Perturbations ◽  
The Hill

Context. The discovery of distant trans-Neptunian objects has led to heated discussions about the structure of the outer Solar System. Aims. We study the dynamical evolution of small bodies from the Hill regions of migrating giant gaseous clumps that form in the outer solar nebula via gravitational fragmentation. We attempt to determine whether the observed features of the orbital distribution of distant trans-Neptunian objects could be caused by this process. Methods. We consider a simple model that includes the Sun, two point-like giant clumps with masses of ∼10 Jupiter masses, and a set of massless objects initially located in the Hill regions of these clumps. We carry out numerical simulations of the motions of small bodies under gravitational perturbations from two giant clumps that move in elliptical orbits and approach each other. The orbital distribution of these small bodies is compared with the observed distribution of distant trans-Neptunian objects. Results. In addition to the known grouping in longitudes of perihelion, we note new features for observed distant trans-Neptunian objects. The observed orbital distribution points to the existence of two groups of distant trans-Neptunian objects with different dynamical characteristics. We show that the main features of the orbital distribution of distant trans-Neptunian objects can be explained by their origin in the Hill regions of migrating giant gaseous clumps. Small bodies are ejected from the Hill regions when the giant clumps move in high-eccentricity orbits and have a close encounter with each other. Conclusions. The resulting orbital distribution of small bodies in our model and the observed distribution of distant trans-Neptunian objects have similar features.

scholarly journals Dynamically Driven Inflow onto the Galactic Center and its Effect upon Molecular Clouds

2021 ◽  
Vol 922 (1) ◽  
pp. 79
Author(s):  
H Perry Hatchfield ◽  
Mattia C. Sormani ◽  
Robin G. Tress ◽  
Cara Battersby ◽  
Rowan J. Smith ◽  
...  
Keyword(s):  
Molecular Clouds ◽  
Galactic Center ◽  
Critical Role ◽  
Average Density ◽  
Gas Flows ◽  
Hydrodynamic Simulations ◽  
Tracer Particles ◽  
Formation And Evolution ◽  
Self Gravity ◽  
Total Inflow

Abstract The Galactic bar plays a critical role in the evolution of the Milky Way’s Central Molecular Zone (CMZ), driving gas toward the Galactic Center via gas flows known as dust lanes. To explore the interaction between the CMZ and the dust lanes, we run hydrodynamic simulations in arepo, modeling the potential of the Milky Way’s bar in the absence of gas self-gravity and star formation physics, and we study the flows of mass using Monte Carlo tracer particles. We estimate the efficiency of the inflow via the dust lanes, finding that only about a third (30% ± 12%) of the dust lanes’ mass initially accretes onto the CMZ, while the rest overshoots and accretes later. Given observational estimates of the amount of gas within the Milky Way’s dust lanes, this suggests that the true total inflow rate onto the CMZ is 0.8 ± 0.6 M ⊙ yr−1. Clouds in this simulated CMZ have sudden peaks in their average density near the apocenter, where they undergo violent collisions with inflowing material. While these clouds tend to counter-rotate due to shear, co-rotating clouds occasionally occur due to the injection of momentum from collisions with inflowing material (∼52% are strongly counter-rotating, and ∼7% are strongly co-rotating of the 44 cloud sample). We investigate the formation and evolution of these clouds, finding that they are fed by many discrete inflow events, providing a consistent source of gas to CMZ clouds even as they collapse and form stars.

scholarly journals Supersonic dusty-gas flows with Knudsen effect in interphase momentum exchange

2004 ◽  
Vol 20 (5) ◽  
pp. 465-470
Author(s):  
Wang Boyi ◽  
A. N. Osiptsov ◽  
L. A. Egorova ◽  
V. I. Sakharov
Keyword(s):  
Gas Flows ◽  
Dusty Gas ◽  
Momentum Exchange ◽  
Knudsen Effect

Modeling Avascular Tumor Growth: Approach with an Adaptive Grid Numerical Technique

2018 ◽  
Vol 09 (03) ◽  
pp. 1840002
Author(s):  
Antonino Amoddeo
Keyword(s):  
Numerical Technique ◽  
Nonlinear Partial Differential Equations ◽  
Dynamical Evolution ◽  
Short Review ◽  
Model Parameters ◽  
Cancer Evolution ◽  
Cancer Proliferation ◽  
In Vivo Experiments ◽  
Spatio Temporal

The mathematical modeling of complex biological systems leads to system of coupled nonlinear partial differential equations (PDEs). In this paper, we present a short review on the interaction of the urokinase plasminogen activator (uPA) system with a model for cancer cell in the avascular phase, faced using the moving mesh PDE/(MMPDE) numerical technique. The dynamical evolution of the system as a function of the diffusion properties of cancer cells has been considered, as well as the effect of hypoxia to the cancer evolution, introducing a model equation for the nutrient oxygen. The model parameters have been taken from the data existing in the literature, in particular to gauge the oxygen supply, data determined from in vivo experiments on human tumors have been used. The numerical results obtained simulating a one-dimensional portion of the biological tissue are consistent with the data existing in the literature. Our high-resolution computations show that cancer proliferation begins through highly irregular spatio-temporal pattern, which depends on cancer motility characteristics. In presence of hypoxia, the cancer proliferation patterns are still characterized by an inhomogeneous pattern, but other effects are present which depend on the model parameters, triggered by the oxygen.

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