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A highly favoured mechanism of planetesimal formation is collisional growth. Single dust grains, which follow gas flows in the protoplanetary disc, hit each other, stick due to van der Waals forces and form fluffy aggregates up to…

Earth and Planetary Astrophysics · Physics 2015-05-14 Ralf J. Geretshauser , Roland Speith , Carsten Güttler , Maya Krause , Jürgen Blum

In the recent years, sub/mm observations of protoplanetary disks have discovered an incredible diversity of substructures in the dust emission. An important result was the finding that dust grains of mm size are embedded in very thin dusty…

Earth and Planetary Astrophysics · Physics 2021-06-23 Mario Flock , Andrea Mignone

The treatment of dust attenuation is crucial in order to compare the predictions of galaxy formation models with multiwavelength observations. Most past studies have either used simple analytic prescriptions or else full radiative transfer…

Astrophysics · Physics 2009-11-13 Fabio Fontanot , Rachel S. Somerville , Laura Silva , Pierluigi Monaco , Ramin Skibba

We propose a dynamic domain semi-Lagrangian method for stochastic Vlasov equations driven by transport noises, which arise in plasma physics and astrophysics. This method combines the volume-preserving property of stochastic characteristics…

Numerical Analysis · Mathematics 2026-03-06 Jianbo Cui , Derui Sheng , Chenhui Zhang , Tau Zhou

To increase the training speed of distributed learning, recent years have witnessed a significant amount of interest in developing both synchronous and asynchronous distributed stochastic variance-reduced optimization methods. However, all…

Machine Learning · Computer Science 2022-08-30 Zhuqing Liu , Xin Zhang , Jia Liu

Recent applications (e.g. active gels and self-assembly of elastic sheets) motivate the need to efficiently simulate the dynamics of thin elastic sheets. We present semi-implicit time stepping algorithms to improve the time step constraints…

Computational Physics · Physics 2019-10-23 Silas Alben , Alex A. Gorodetsky , Donghak Kim , Robert D. Deegan

We present the Stagger-grid, a comprehensive grid of time-dependent, 3D hydrodynamic model atmospheres for late-type stars with realistic treatment of radiative transfer, covering a wide range in stellar parameters. This grid of 3D models…

Solar and Stellar Astrophysics · Physics 2015-06-15 Z. Magic , R. Collet , M. Asplund , R. Trampedach , W. Hayek , A. Chiavassa , R. F. Stein , Å. Nordlund

We review progress that has been made in utilizing one form of Direct Statistical Simulation (DSS) to describe geophysical and astrophysical flows that are anisotropic and inhomogeneous. We first explain the approach, which is based upon a…

Fluid Dynamics · Physics 2019-03-19 J. B. Marston , Wanming Qi , S. M. Tobias

Next-generation photometric and spectroscopic surveys will detect faint galaxies in massive clusters, advancing our understanding of galaxy formation in dense environments. Comparing these observations with theoretical models requires…

Astrophysics of Galaxies · Physics 2025-05-19 Jonathan S. Gómez , Tomas Hough , Alejandro Jiménez Muñoz , Gustavo Yepes , Weiguang Cui , Sofía A. Cora

Obtaining accurate estimates of satellite drag coefficients in low Earth orbit is a crucial component in positioning and collision avoidance. Simulators can produce accurate estimates, but their computational expense is much too large for…

Computation · Statistics 2019-06-25 Furong Sun , Robert B. Gramacy , Benjamin Haaland , Earl Lawrence , Andrew Walker

We propose a new metaheuristic training scheme that combines Stochastic Gradient Descent (SGD) and Discrete Optimization in an unconventional way. Our idea is to define a discrete neighborhood of the current SGD point containing a number of…

Machine Learning · Computer Science 2019-06-05 Matteo Fischetti , Matteo Stringher

Planet formation in the discs around young stars involves the coagulation of sub-micron sized dust grains into much larger grains that may be mixed by turbulence and migrate through the disc. In this paper, we describe how we have combined…

Earth and Planetary Astrophysics · Physics 2026-02-04 Matthew R. Bate , Mark A. Hutchison , Daniel Elsender

Dust plays a key role during star, disk and planet formation. Yet, its dynamics during the protostellar collapse remains a poorly investigated field. Recent studies seem to indicate that dust may decouple efficiently from the gas during…

Solar and Stellar Astrophysics · Physics 2020-09-23 Ugo Lebreuilly , Benoît Commerçon , Guillaume Laibe

When the output of an atomistic simulation (such as the Gillespie stochastic simulation algorithm, SSA) can be approximated as a diffusion process, we may be interested in the dynamic features of the deterministic (drift) component of this…

Statistical Mechanics · Physics 2007-05-23 C. P. Calderon , G. A. Tsekouras , A. Provata , I. G. Kevrekidis

In a companion paper we have shown how the equations describing gas and dust as two fluids coupled by a drag term can be reformulated to describe the system as a single fluid mixture. Here we present a numerical implementation of the…

Earth and Planetary Astrophysics · Physics 2015-06-18 Guillaume Laibe , Daniel J. Price

Protoplanetary disks exhibit a vertical gradient in angular momentum, rendering them susceptible to the Vertical Shear Instability (VSI). The most important condition for the onset of this mechanism is a short timescale of thermal…

Earth and Planetary Astrophysics · Physics 2023-12-18 Thomas Pfeil , Til Birnstiel , Hubert Klahr

Dust grains play a major role in many astrophysical contexts. They affect the chemical, magnetic, dynamical, and optical properties of their environment, from galaxies down to the interstellar medium, star-forming regions, and…

Astrophysics of Galaxies · Physics 2021-05-18 Pierre Marchand , Vincent Guillet , Ugo Lebreuilly , Mordecai-Mark Mac Low

We have developed a new numerical technique for simulating dusty-gas flows. Our unique code incorporates gas hydrodynamics, self-gravity and dust drag to follow the dynamical evolution of a dusty-gas medium. We have incorporated several…

Astrophysics · Physics 2007-05-23 S. T. Maddison , R. J. Humble , J. R. Murray

We describe the algorithm, implementation and numerical tests of a multifluid dust module in the Athena++ magnetohydrodynamic (MHD) code. The module can accommodate an arbitrary number of dust species interacting with the gas via…

Earth and Planetary Astrophysics · Physics 2022-08-31 Pinghui Huang , Xue-Ning Bai

Many relevant problems in the area of systems and control, such as controller synthesis, observer design and model reduction, can be viewed as optimization problems involving dynamical systems: for instance, maximizing performance in the…

Optimization and Control · Mathematics 2023-11-15 Pascal Den Boef , Jos Maubach , Wil Schilders , Nathan van de Wouw