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A time-distance helioseismic technique, similar to the one used by Ilonidis et al (2011), is applied to two independent numerical models of subsurface sound-speed perturbations to determine the spatial resolution and accuracy of phase…

Solar and Stellar Astrophysics · Physics 2021-06-02 John T. Stefan , Alexander G. Kosovichev , Andrey M. Stejko

We present results from fitting $p$-mode spectra derived from 7-d segments of Sun-as-a-star helioseismic observations from the Birmingham Solar Oscillations Network covering 32 yr. The results show a clear dependence of the mode frequencies…

Solar and Stellar Astrophysics · Physics 2025-01-15 R. Howe , W. J. Chaplin , Y. P. Elsworth , S. J. Hale , E. Hatt , M. B. Nielsen

We propose a method to parameterize a coarse grained model for the hydrodynamic friction between nearly touching rough spheres in suspension flows. The frictional resistance due to surface roughness primarily alters the sliding and rolling…

Soft Condensed Matter · Physics 2022-03-15 Madhu V. Majji , James W. Swan

Context. The interaction of solar oscillations with near surface convection is poorly understood. These interactions are likely the cause of several problems in helio- and astero-seismology, including the so-called surface effect and…

Solar and Stellar Astrophysics · Physics 2015-08-19 J. Schou

The amount of turbulent pressure in galaxy clusters is still debated, especially as for the impact of the dynamical state and the hydro-method used for simulations. We study the turbulent pressure fraction in the intra cluster medium of…

Cosmology and Nongalactic Astrophysics · Physics 2025-01-29 Frederick Groth , Milena Valentini , Ulrich P. Steinwandel , David Vallés-Pérez , Klaus Dolag

The computation of damping rates of an oscillating fluid with a free surface in which viscosity is small and surface tension high is numerically challenging. A typical application requiring such computation is drop-on-demand (DoD)…

Computational Physics · Physics 2024-12-11 Søren Taverniers , Svyatoslav Korneev , Christoforos Somarakis , Morad Behandish , Adrian J. Lew

We formulate theoretical modeling approaches and develop practical computational simulation methods for investigating the non-equilibrium statistical mechanics of fluid interfaces with passive and active immersed particles. Our approaches…

Soft Condensed Matter · Physics 2024-10-03 Dev Jasuja , Paul J. Atzberger

The paper develops a method for the numerical simulation of a free-surface flow of incompressible viscous fluid around a streamlined body. The body is a rigid stationary construction partially submerged in the fluid. The application we are…

Being able to image active regions on the Sun's far side is useful for modeling the global-scale magnetic field around the Sun, and for predicting the arrival of major active regions that rotate around the limb onto the near side.…

Solar and Stellar Astrophysics · Physics 2020-01-08 Junwei Zhao , Dominick Hing , Ruizhu Chen , Shea Hess Webber

This paper aims at investigating the existence of localized stationary waves in the shallow subsurface whose constitutive behaviour is governed by the hyperbolic model, implying non-polynomial nonlinearity and strain-dependent shear…

Context. The spatial power spectrum of supergranulation does not fully characterize the underlying physics of turbulent convection. For example, it does not describe the non-Gaussianity in the horizontal flow divergence. Aims. Our aim is to…

Solar and Stellar Astrophysics · Physics 2020-04-01 Vincent G. A. Böning , Aaron C. Birch , Laurent Gizon , Thomas L. Duvall , Jesper Schou

We present a numerical simulation of a granular material using hydrodynamic equations. We show that, in the absence of external forces, such a system phase-separates into high density and low density regions. We show that this separation is…

Soft Condensed Matter · Physics 2009-11-07 Scott A. Hill , Gene F. Mazenko

The computationally demanding nature of radiative-hydrodynamical simulations of stellar surface convection warrants an investigation of the sensitivity of the convective structure and spectral synthesis to the numerical resolution and…

Astrophysics · Physics 2007-05-23 M. Asplund , H. -G. Ludwig , AA. Nordlund , R. F. Stein

Helioseismology has provided very precise information about the solar internal sound speed and density throughout most of the solar interior. The results are generally quite close to the properties of standard solar models. Since the solar…

Astrophysics · Physics 2007-05-23 J. Christensen-Dalsgaard

Quantitative helio- and asteroseismology require very precise measurements of the frequencies, amplitudes, and lifetimes of the global modes of stellar oscillation. It is common knowledge that the precision of these measurements depends on…

Astrophysics · Physics 2009-11-13 Thorsten Stahn , Laurent Gizon

Context : On its asteroseismic side, the initial run of CoRoT was partly devoted to the solar like star HD49933.The eigenmodes of this F dwarf have been observed with unprecedented accuracy. Aims : We investigate quantitatively the impact…

Solar and Stellar Astrophysics · Physics 2015-05-13 L. Piau , S. Turck-Chieze , V. Duez , R. F. Stein

In this article we report on a study of the near-wall dynamics of suspended colloidal hard spheres over a broad range of volume fractions. We present a thorough comparison of experimental data with predictions based on a virial…

Dynamics of linear perturbations in a differentially rotating accretion disk with non-homogeneous vertical structure is investigated. It has been found that turbulent viscosity results in instability of both pinching oscillations, and…

Astrophysics · Physics 2007-05-23 A. V. Khoperskov , S. S. Khrapov

Fault systems have geometrically complex structures in nature, such as stepovers, bends, branches, and roughness. Many geological and geophysical studies have shown that the geometrical complexity of fault systems in nature decisively…

The numerical simulation of acoustic waves in complex 3D media is a key topic in many branches of science, from exploration geophysics to non-destructive testing and medical imaging. With the drastic increase in computing capabilities this…

Computational Physics · Physics 2016-12-21 Alexis Bottero , Paul Cristini , Dimitri Komatitsch , Mark Asch