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We show that the multi-dimensional compressible Euler system for isothermal flow of an ideal, polytropic gas admits global-in-time, radially symmetric solutions with unbounded amplitudes due to wave focusing. The examples are similarity…

Analysis of PDEs · Mathematics 2020-05-26 Helge Kristian Jenssen , Charis Tsikkou

Context: Dynamical studies of irradiated circumstellar disks require an accurate treatment of radiation transport to, for example, properly determine cooling and fragmentation properties. The radiation transport algorithm should be as fast…

Solar and Stellar Astrophysics · Physics 2013-06-20 Rolf Kuiper , Ralf S. Klessen

Inertial range scaling exponents for both Lagrangian and Eulerian structure functions are obtained from direct numerical simulations of isotropic turbulence in triply periodic domains at Taylor-scale Reynolds number up to 1300. We reaffirm…

Fluid Dynamics · Physics 2024-03-05 Dhawal Buaria , Katepalli R. Sreenivasan

Eulerian and Lagrangian tools are used to detect coherent structures in the velocity and magnetic fields of a mean--field dynamo, produced by direct numerical simulations of the three--dimensional compressible magnetohydrodynamic equations…

Solar and Stellar Astrophysics · Physics 2013-11-21 Erico L. Rempel , Abraham C. -L. Chian , Axel Brandenburg , Pablo R. Muñoz

In this paper, a hybrid Lagrangian-Eulerian topology optimization (LETO) method is proposed to solve the elastic force equilibrium with the Material Point Method (MPM). LETO transfers density information from freely movable Lagrangian…

Computational Physics · Physics 2021-04-14 Yue Li , Xuan Li , Minchen Li , Yixin Zhu , Bo Zhu , Chenfanfu Jiang

In Klingenberg, Schn\"ucke and Xia (Math. Comp. 86 (2017), 1203-1232) an arbitrary Lagrangian-Eulerian discontinuous Galerkin (ALE-DG) method to solve conservation laws has been developed and analyzed. In this paper, the ALE-DG method will…

Numerical Analysis · Mathematics 2018-12-27 Pei Fu , Gero Schnücke , Yinhua Xia

Global time-dependent simulations provide a means to investigate time-dependent dynamic evolution in accretion disks. This paper seeks to extend previous local simulations by beginning a systematic effort to develop fully global…

Astrophysics · Physics 2009-10-31 John F. Hawley

The evolution of a Taylor-Green forced magnetohydrodynamic (MHD) system showing dynamo activity is analyzed via direct numerical simulations. The statistical properties of the velocity and magnetic field in Eulerian coordinates and along…

Fluid Dynamics · Physics 2015-06-17 Holger Homann , Yannick Ponty , Giorgio Krstulovic , Rainer Grauer

We present a coupled Eulerian-Lagrangian method to simulate cloud cavitation in a compressible liquid. The method is designed to capture the strong, volumetric oscillations of each bubble and the bubble-scattered acoustics. The dynamics of…

Fluid Dynamics · Physics 2018-06-12 Kazuki Maeda , Tim Colonius

The explicit semi-Lagrangian method method for solution of Lagrangian transport equations as developed in [Natarajan and Jacobs, Computer and Fluids, 2020] is adopted for the solution of stochastic differential equations that is consistent…

Computational Physics · Physics 2021-07-07 H. Natarajan , P. P. Popov , G. B. Jacobs

Recent radiation-thermochemical-magnetohydrodynamic simulations resolved formation of quasar accretion disks from cosmological scales down to ~300 gravitational radii $R_{g}$, arguing they were 'hyper-magnetized' (plasma $\beta\ll1$…

Currently, Eulerian flow solvers are very efficient in accurately resolving flow structures near solid boundaries. On the other hand, they tend to be diffusive and to dampen high-intensity vortical structures after a short distance away…

Numerical Analysis · Mathematics 2015-06-05 Artur Palha , Lento Manickathan , Carlos Simao Ferreira , Gerard van Bussel

The standard thin disk model predicts that when the accretion rate is over a small fraction of the Eddington rate, which corresponds to $L \ga 0.06 L_{Edd}$, the inner region of the disk is radiation-pressure-dominated and thermally…

High Energy Astrophysical Phenomena · Physics 2015-05-27 Sheng-Ming Zheng , Feng Yuan , Wei-Min Gu , Ju-Fu Lu

The theory of elastic magnets is formulated under possible diffusion and heat flow governed by Fick's and Fourier's laws in the deformed (Eulerian) configuration, respectively. The concepts of nonlocal nonsimple materials and viscous…

Mathematical Physics · Physics 2018-05-09 Tomas Roubicek , Giuseppe Tomassetti

The frozen Gaussian approximation, proposed in [Lu and Yang, [15]], is an efficient computational tool for high frequency wave propagation. We continue in this paper the development of frozen Gaussian approximation. The frozen Gaussian…

Numerical Analysis · Mathematics 2011-08-01 Jianfeng Lu , Xu Yang

This manuscript concerns the stability conditions for the well-posedness of the two-dimensional plasma-vacuum interface problems for ideal incompressible magnetohydrodynamics (MHD) equations, which describe the dynamics of conducting…

Analysis of PDEs · Mathematics 2025-07-21 Sicheng Liu , Tao Luo

We study dust transport in turbulent protoplanetary disks using three-dimensional global unstratified magnetohydrodynamic (MHD) simulations including Lagrangian dust particles. The turbulence is driven by the magnetorotational instability…

Earth and Planetary Astrophysics · Physics 2015-06-19 Zhaohuan Zhu , James M. Stone , Xue-Ning Bai

There are several plasma models intermediate in complexity between ideal magnetohydrodynamics (MHD) and two-fluid theory, with Hall and Extended MHD being two important examples. In this paper we investigate several aspects of these…

Plasma Physics · Physics 2016-06-07 E. C. D'Avignon , P. J. Morrison , M. Lingam

Magnetorotational instability (MRI) is the most promising mechanism behind accretion in low-mass protostellar disks. Here we present the first analysis of the global structure and evolution of non-ideal MRI-driven T-Tauri disks on…

Earth and Planetary Astrophysics · Physics 2015-06-15 Russell Landry , Sarah E. Dodson-Robinson , Neal J. Turner , Greg Abram

We present a new high-order accurate Lagrangian discontinuous Galerkin (DG) hydrodynamic method to simulate material dynamics (for e.g., gasses, fluids, and solids) with up to fourth-order accuracy on cubic meshes. The variables, such as…

Computational Physics · Physics 2021-03-04 Xiaodong Liu , Nathaniel R. Morgan , Evan J. Lieberman , Donald E. Burton