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Related papers: Accurate Diffusion Coefficients for Dense White Dw…

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In this paper we study the diffusion approximation of a swarming model given by a system of interacting Langevin equations with nonlinear friction. The diffusion approximation requires the calculation of the drift and diffusion coefficients…

Numerical Analysis · Mathematics 2015-05-08 V. Bonnaillie-Noël , J. A. Carrillo , T. Goudon , G. A. Pavliotis

Metastable condensed matter typically fluctuates about local energy minima at the femtosecond time scale before transitioning between local minima after nanoseconds or microseconds. This vast scale separation limits the applicability of…

Computational Physics · Physics 2017-11-22 Brittan A Farmer , Mitchell Luskin , Petr Plecháč , Gideon Simpson

We determine the ratio of helium- to hydrogen-atmosphere white dwarf stars as a function of effective temperature from a model atmosphere analysis of the infrared photometric data from the Two Micron All Sky Survey combined with available…

Astrophysics · Physics 2009-11-13 P. -E. Tremblay , P. Bergeron

White dwarf asteroseismology offers the opportunity to probe the structure and composition of stellar objects governed by relatively simple physical principles. The observational requirements of asteroseismology have been addressed by the…

Astrophysics · Physics 2009-11-06 Travis S. Metcalfe

The diffusion of atoms and radicals on interstellar dust grains is a fundamental ingredient for predicting accurate molecular abundances in astronomical environments. Quantitative values of diffusivity and diffusion barriers usually rely…

Astrophysics of Galaxies · Physics 2021-12-22 Viktor Zaverkin , Germán Molpeceres , Johannes Kästner

Diffusion models excel at capturing the natural design spaces of images, molecules, DNA, RNA, and protein sequences. However, rather than merely generating designs that are natural, we often aim to optimize downstream reward functions while…

In this work, we aimed to replicate and extend the results presented in the DiffFluid paper[1]. The DiffFluid model showed that diffusion models combined with Transformers are capable of predicting fluid dynamics. It uses a denoising…

Fluid Dynamics · Physics 2025-07-14 Yannick Gachnang , Vismay Churiwala

In physics, density $\rho(\cdot)$ is a fundamentally important scalar function to model, since it describes a scalar field or a probability density function that governs a physical process. Modeling $\rho(\cdot)$ typically scales poorly…

Computational Physics · Physics 2023-12-14 Maxwell X. Cai , Kin Long Kelvin Lee

In this work, a coarse-graining method previously proposed by the authors in a companion paper based on solving diffusion equations is applied to CFD-DEM simulations, where coarse graining is used to obtain solid volume fraction, particle…

Computational Physics · Physics 2015-01-07 Rui Sun , Heng Xiao

Polluted white dwarfs (WDs) with small surface convection zones deposit significant concentrations of heavy elements to the underlying radiative interior, presumably driving thermohaline convection. Current models of polluted WDs frequently…

Solar and Stellar Astrophysics · Physics 2025-03-28 Imogen G. Cresswell , Adrian E. Fraser , Evan B. Bauer , Evan H. Anders , Benjamin P. Brown

Swimming bacteria create long-range velocity fields that stir a large volume of fluid and move around passive particles dispersed in the fluid. Recent experiments and simulations have shown that long-time mean-squared displacement of…

Soft Condensed Matter · Physics 2013-08-20 Alexander Morozov , Davide Marenduzzo

We demonstrate a new Bayesian technique to invert color-magnitude diagrams of main sequence and white dwarf stars to reveal the underlying cluster properties of age, distance, metallicity, and line-of-sight absorption, as well as individual…

Self- and binary Maxwell-Stefan diffusion coefficients were determined by equilibrium molecular dynamics simulations with the Green-Kubo method. This study covers self-diffusion coefficients at liquid states for eight pure fluids, i.e.…

Chemical Physics · Physics 2009-04-30 Gimmy Alex Fernandez Ramirez , Jadran Vrabec , Hans Hasse

Diffusion models represent a powerful family of generative models widely used for image and video generation. However, the time-consuming deployment, long inference time, and requirements on large memory hinder their applications on…

Machine Learning · Computer Science 2025-04-18 Kafeng Wang , Jianfei Chen , He Li , Zhenpeng Mi , Jun Zhu

We present a detailed analysis of 108 helium-line (DB) white dwarfs based on model atmosphere fits to high signal-to-noise optical spectroscopy. We derive a mean mass of 0.67 Mo for our sample, with a dispersion of only 0.09 Mo. White…

Computational fluid dynamics (CFD) is a powerful tool for modeling turbulent flow and is commonly used for urban microclimate simulations. However, traditional CFD methods are computationally intensive, requiring substantial hardware…

Diffusion in an evolving environment is studied by continuos-time Monte Carlo simulations. Diffusion is modelled by continuos-time random walkers on a lattice, in a dynamic environment provided by bubbles between two one-dimensional…

Soft Condensed Matter · Physics 2010-11-22 Janne Juntunen , Juha Merikoski

Surface chemistry on interstellar dust grains is recognized as a central component in astrochemical models, representing a plausible formation route for many of the observed complex molecular species. However, key parameters governing…

Astrophysics of Galaxies · Physics 2026-01-22 Francesco Benedetti , Mauro Satta , Tommaso Grassi , Stefan Vogt-Geisse , Stefano Bovino

A growing sample of white dwarfs (WDs) with metal-enriched atmospheres are accompanied by excess infrared emission, indicating that they are encircled by a compact dusty disk of solid debris. Such `WD debris disks' are thought to originate…

Earth and Planetary Astrophysics · Physics 2015-06-04 Brian D. Metzger , Roman R. Rafikov , Konstantin V. Bochkarev

A non negligible fraction of white dwarf stars show the presence of heavy elements in their atmospheres. The most accepted explanation for this contamination is the accretion of material coming from tidally disrupted planetesimals, which…

Solar and Stellar Astrophysics · Physics 2022-04-13 F. C. Wachlin , G. Vauclair , S. Vauclair , L. G. Althaus