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Particle Image Velocimetry (PIV) has become increasingly popular to study structures in turbulent flows. PIV allows direct extraction and investigation of spatial structures in the given flow field. Increasing temporal resolution of PIV…

Fluid Dynamics · Physics 2021-12-10 Tom T. B. Wester , André Fuchs , Joachim Peinke , Gerd Gülker

A new method to describe hyperbolic patterns in two dimensional flows is proposed. The method is based on the Covariant Lyapunov Vectors (CLVs), which have the properties to be covariant with the dynamics, and thus being mapped by the…

Chaotic Dynamics · Physics 2017-09-29 Giovanni Conti , Gualtiero Badin

The second entropy theory for non-equilibrium thermodynamics is used to show that the optimum structure or pattern of a time-dependent system corresponds to the maximum entropy. A formula for the total entropy of convective heat flow is…

Statistical Mechanics · Physics 2012-09-11 Phil Attard

Broadening and asymmetry of spectral lines in slowly rotating late A-type stars provide evidence for high-amplitude convective motions. The properties of turbulence observed in the A-star atmospheres are not understood theoretically and…

Astrophysics · Physics 2015-06-24 O. Kochukhov , B. Freytag , N. Piskunov , M. Steffen

We investigate the onset and evolution of zonal flows in a growing convective layer when a stably-stratified fluid with a composition gradient is cooled from above. This configuration allows the study of zonal flows for a wide range of…

Fluid Dynamics · Physics 2023-11-08 J. R. Fuentes , A. Cumming

We present a hydrodynamic model that captures the essence of granular dynamics in a vibrating bed. We carry out the linear stability analysis and uncover the instability mechanism that leads to the appearance of the convective rolls via a…

adap-org · Physics 2015-06-30 Hisao Hayakawa , Su Yue , Daniel C. Hong

Within the current uncertainties in the treatment of the coupling between pulsation and convection, limiting amplitude, nonlinear, convective models appear the only viable approach for providing theoretical predictions about the intrinsic…

Astrophysics · Physics 2009-10-31 G. Bono , V. Castellani , M. Marconi

We have developed a multidimensional radiation hydrodynamics code to simulate the interaction of radial stellar pulsation and convection for full amplitude pulsating models. Convection is computed using large eddy simulations. Here we…

Solar and Stellar Astrophysics · Physics 2014-03-05 Christopher M. Geroux , Robert G. Deupree

Starting from full-dimensional models of solute transport, we derive and analyze multi-dimensional models of time-dependent convection, diffusion, and exchange in and around pulsating vascular and perivascular networks. These models are…

Analysis of PDEs · Mathematics 2023-04-03 Rami Masri , Marius Zeinhofer , Miroslav Kuchta , Marie E. Rognes

High-resolution images of the solar surface show a granulation pattern of hot rising and cooler downward-sinking material -- the top of the deep-reaching solar convection zone. Convection plays a role for the thermal structure of the solar…

Solar and Stellar Astrophysics · Physics 2011-12-14 Bernd Freytag , Matthias Steffen , Hans-Günter Ludwig , Sven Wedemeyer-Böhm , Werner Schaffenberger , Oskar Steiner

Rayleigh--B\'enard convection, which is the buoyancy-induced motion of a fluid enclosed between two horizontal plates, is an idealised setup to study thermal convection. We analyse the modes that transport the most heat between the plates…

Fluid Dynamics · Physics 2015-10-26 Johannes Lülff

In a companion paper, we develop a theory for the evolution of stellar wind driven bubbles in dense, turbulent clouds. This theory proposes that turbulent mixing at a fractal bubble-shell interface leads to highly efficient cooling, in…

Astrophysics of Galaxies · Physics 2021-06-30 Lachlan Lancaster , Eve C. Ostriker , Jeong-Gyu Kim , Chang-Goo Kim

Context: The paradigm of convection in solar-like stars is questioned based on recent solar observations. Aims: The primary aim is to study the effects of surface-driven entropy rain on convection zone structure and flows. Methods:…

Solar and Stellar Astrophysics · Physics 2025-06-11 P. J. Käpylä

The extent of mixed regions around convective zones is one of the biggest uncertainties in stellar evolution. 1D overshooting descriptions introduce a free parameter ($f_{ov}$) that is in general not well constrained from observations.…

Solar and Stellar Astrophysics · Physics 2021-03-08 Johann Higl , Ewald Mueller , Achim Weiss

We present a new model of large-scale multilayer convection in solar type stars. This model allows us to understand such self-similar structures observed at solar surface as granulation, supergranulation and giant cells. We study the…

Solar and Stellar Astrophysics · Physics 2010-12-17 E. A. Bruevich , I. K. Rozgacheva

The ANTARES code has been designed for simulation of astrophysical flows in a variety of situations, in particular in the context of stellar physics. Here, we describe extensions as necessary to model the interaction of pulsation and…

Solar and Stellar Astrophysics · Physics 2011-11-15 Eva Mundprecht , Herbert J. Muthsam

We perform three dimensional radiation hydrodynamic simulations of the structure and dynamics of radiation dominated envelopes of massive stars at the location of the iron opacity peak. One dimensional hydrostatic calculations predict an…

Solar and Stellar Astrophysics · Physics 2015-11-04 Yan-Fei Jiang , Matteo Cantiello , Lars Bildsten , Eliot Quataert , Omer Blaes

This paper proposes a physical-statistical modeling approach for spatio-temporal data arising from a class of stochastic convection-diffusion processes. Such processes are widely found in scientific and engineering applications where…

Applications · Statistics 2020-08-07 Xiao Liu , Kyongmin Yeo , Siyuan Lu

Context. The surface structures and dynamics of cool stars are characterized by the presence of convective motions and turbulent flows which shape the emergent spectrum. Aims. We used realistic three-dimensional radiative hydrodynamical…

Solar and Stellar Astrophysics · Physics 2018-03-14 A. Chiavassa , L. Casagrande , R. Collet , Z. Magic , L. Bigot , F. Thevenin , M. Asplund

The paper presents the results of three-dimensional (3D) modelling of the structure and the emission of accretion columns formed above the surface of accreting strongly magnetized neutron stars under the circumstances when a pressure of the…

High Energy Astrophysical Phenomena · Physics 2020-12-22 M. I. Gornostaev