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We compute solutions of the Lagrangian-Averaged Navier-Stokes alpha-model (LANS) for significantly higher Reynolds numbers (up to Re 8300) than have previously been accomplished. This allows sufficient separation of scales to observe a…

Fluid Dynamics · Physics 2007-11-15 J. Pietarila Graham , Darryl Holm , Pablo Mininni , Annick Pouquet

Unsteady Lifting-Line Theory (ULLT) is a low order method capable of modeling interacting unsteady and finite wing effects at low computational cost. Most formulations of the method assume inviscid flow and small amplitudes. Whilst these…

Fluid Dynamics · Physics 2021-04-14 Hugh J. A. Bird , Kiran Ramesh , Shūji Ōtomo , Ignazio Maria Viola

In this paper we overcome a key problem in an otherwise highly potential approach to study turbulent flows, ODTLES (One-Dimensional Turbulence Large Eddy Simulation). From a methodological point of view, ODTLES is an approach in between…

Fluid Dynamics · Physics 2018-06-06 Christoph Glawe , Juan A. Medina M. , Heiko Schmidt

In this paper, the three-dimensional (3D) isentropic compressible Navier-Stokes equations with degenerate viscosities (\textbf{ICND}) is considered in both the whole space and the periodic domain. First, for the corresponding Cauchy…

Analysis of PDEs · Mathematics 2019-11-20 Shengguo Zhu

3D hydrodynamics models of deep stellar convection exhibit turbulent entrainment at the convective-radiative boundary which follows the entrainment law, varying with boundary penetrability. We implement the entrainment law in the 1D Geneva…

Solar and Stellar Astrophysics · Physics 2021-03-24 L. J. A. Scott , R. Hirschi , C. Georgy , W. D. Arnett , C. Meakin , E. A. Kaiser , S. Ekström , N. Yusof

We are concerned with the long-time behavior of classical solutions to the isentropic compressible Navier-Stokes equations in $\mathbb R^3$. Our main results and innovations can be stated as follows: Under the assumption that the density…

Analysis of PDEs · Mathematics 2024-11-05 Guochun Wu , Xin Zhong

We prove the existence and uniqueness of global, probabilistically strong, analytically strong solutions of the 2D Stochastic Navier-Stokes Equation under Navier boundary conditions. The choice of noise includes a large class of additive,…

Probability · Mathematics 2023-08-17 Daniel Goodair

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

Turbulent problems in industrial applications are predominantly solved using Reynolds Averaged Navier Stokes (RANS) turbulence models. The accuracy of the RANS models is limited due to closure assumptions that induce uncertainty into the…

Fluid Dynamics · Physics 2018-02-20 Atieh Alizadeh Moghaddam , Amir Sadaghiyani

Numerical simulations of magneto-convection have greatly expanded our understanding of stellar interiors and stellar magnetism. Recently, fully compressible hydrodynamical simulations of full-star models have demonstrated the feasibility of…

Solar and Stellar Astrophysics · Physics 2022-08-03 José R. Canivete Cuissa , Romain Teyssier

The interaction among quasi-geostrophic mesoscale eddies, submesoscale fronts, and boundary layer turbulence (BLT) is a central problem in upper ocean dynamics. We investigate these multiscale dynamics using a novel large-eddy simulation on…

Fluid Dynamics · Physics 2026-04-21 S. Peng , S. Silvestri , A. Bodner

MHD turbulence is likely to play an important role in several astrophysical scenarios where the magnetic Reynolds is very large. Numerically, these cases can be studied efficiently by means of Large Eddy Simulations, in which the…

High Energy Astrophysical Phenomena · Physics 2020-03-25 Federico Carrasco , Daniele Viganò , Carlos Palenzuela

Numerical and analytical studies of decaying, two-dimensional (2D) Navier-Stokes (NS) turbulence at high Reynolds numbers are reported. The effort is to determine computable distinctions between two different formulations of maximum entropy…

Fluid Dynamics · Physics 2009-11-07 Z. Yin , D. C. Montgomery , H. J. H. Clercx

In this paper, we study the dynamic stability of the 3D axisymmetric Navier-Stokes Equations with swirl. To this purpose, we propose a new one-dimensional (1D) model which approximates the Navier-Stokes equations along the symmetry axis. An…

Analysis of PDEs · Mathematics 2007-05-23 Thomas Y. Hou , Congming Li

We present the existence/non-existence criteria for large-amplitude boundary layer solutions to the inflow problem of the one-dimensional (1D) full compressible Navier-Stokes equations on a half line $\mathbb{R}_+$. Instead of the classical…

Analysis of PDEs · Mathematics 2025-05-01 Yi Wang , Yong-Fu Yang , Qiuyang Yu

The outer envelopes of massive ($M\gtrsim10\,M_{\odot}$) stars exhibit large increases in opacities from forests of lines and ionization transitions (particularly from iron and helium) that trigger near-surface convection zones.…

Solar and Stellar Astrophysics · Physics 2023-07-19 William Schultz , Lars Bildsten , Yan-Fei Jiang

We study stochastic Navier-Stokes equations in two dimensions with respect to periodic boundary conditions. The equations are perturbed by a nonlinear multiplicative stochastic forcing with linear growth (in the velocity) driven by a…

Numerical Analysis · Mathematics 2019-07-10 Dominic Breit , Alan Dodgson

Present grids of stellar atmosphere models are the workhorses in interpreting stellar observations, and determining their fundamental parameters. These models rely on greatly simplified models of convection, however, lending less predictive…

Solar and Stellar Astrophysics · Physics 2015-06-15 Regner Trampedach , Martin Asplund , Remo Collet , Åke Nordlund , Robert F. Stein

We consider stochastic approximations of sampling algorithms, such as Stochastic Gradient Langevin Dynamics (SGLD) and the Random Batch Method (RBM) for Interacting Particle Dynamcs (IPD). We observe that the noise introduced by the…

Probability · Mathematics 2023-10-10 Aniket Das , Dheeraj Nagaraj , Anant Raj