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Related papers: Varying the forcing scale in low Prandtl number dy…

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Direct numerical simulations (DNS) of fully-developed turbulent channel flows for very low Reynolds numbers have been performed with a larger computational box sizes than those of existing DNS. The friction Reynolds number was decreased…

Fluid Dynamics · Physics 2014-09-17 Takahiro Tsukahara , Yohji Seki , Hiroshi Kawamura , Daisuke Tochio

We analyze the Prandtl number (Pr) dependence of spectra and fluxes of kinetic energy, as well as the energy injection rates and dissipation rates, of turbulent thermal convection using numerical data. As expected, for a flow with $…

Fluid Dynamics · Physics 2021-06-03 Shashwat Bhattacharya , Mahendra K. Verma , Ravi Samtaney

The turnover of interstellar gas on $\sim 10^9$yr timescales argues for the continuous operation of a galactic dynamo. The conductivity of interstellar gas is so high that the dynamo must be "fast" - i.e. the magnetic field must be…

Astrophysics · Physics 2008-05-06 Ellen G. Zweibel Fabian Heitsch

Nonhelical hydromagnetic turbulence without an imposed magnetic field is considered in the case where the magnetic Prandtl number is unity. The magnetic field is entirely due to dynamo action. The magnetic energy spectrum peaks at a…

Astrophysics · Physics 2007-05-23 Nils Erland L. Haugen , Axel Brandenburg , Wolfgang Dobler

Statistical properties of turbulent Rayleigh-Benard convection at low Prandtl numbers (Pr), which are typical for liquid metals such as mercury, gallium or liquid sodium, are investigated in high-resolution three-dimensional spectral…

Fluid Dynamics · Physics 2016-09-13 Janet D. Scheel , Joerg Schumacher

With a non local shell model of magnetohydrodynamic turbulence we investigate numerically the turbulent dynamo action for low and high magnetic Prandtl numbers ($Pm$). The results obtained in the kinematic regime and along the way to dynamo…

Astrophysics · Physics 2009-11-13 Rodion Stepanov , Franck Plunian

In this letter we investigate the dynamics of magnetic energy growth in small-scale dynamo by studying energy transfers, mainly energy fluxes and shell-to-shell energy transfers. We perform dynamo simulations for magnetic Prandtl number…

Fluid Dynamics · Physics 2014-01-13 Rohit Kumar , Mahendra K. Verma , Ravi Samtaney

Energy cascades lie at the heart of the dynamics of turbulent flows. In a recent study of turbulence in fluids with odd-viscosity [de Wit \textit{et al.}, Nature \textbf{627}, 515 (2024)], the two-dimensionalization of the flow at small…

Fluid Dynamics · Physics 2024-10-22 Kolluru Venkata Kiran , Dario Vincenzi , Rahul Pandit

The chaotic dynamics of small-scale vorticity plays a key role in understanding and controlling turbulence, with direct implications for energy transfer, mixing, and coherent structure evolution. However, measuring or controlling its…

We extend the scaling relations of stably stratified turbulence from the geophysical regime of unity Prandtl number to the astrophysical regime of extremely small Prandtl number applicable to stably stratified regions of stars and gas…

Fluid Dynamics · Physics 2023-02-15 Valentin A. Skoutnev

Magnetic fields are a dynamically important component of the turbulent interstellar medium (ISM) of star-forming galaxies. These magnetic fields are due to a dynamo action, which is a process of converting turbulent kinetic energy to…

Astrophysics of Galaxies · Physics 2022-06-01 Amit Seta , Christoph Federrath

Additional physics beyond standard hydrodynamics is needed to fully model the intracluster medium (ICM); however, as we move to more sophisticated models, it is important to consider the role of magnetic fields and the way the fluid…

Cosmology and Nongalactic Astrophysics · Physics 2016-08-04 Hilary Egan , Brian W. O'Shea , Eric Hallman , Jack Burns , Hao Xu , David Collins , Hui Li , Michael L. Norman

Turbulence in a conducting plasma can amplify seed magnetic fields in what is known as the turbulent, or small-scale, dynamo. The associated growth rate and emergent magnetic-field geometry depend sensitively on the material properties of…

High Energy Astrophysical Phenomena · Physics 2022-10-17 Alisa K. Galishnikova , Matthew W. Kunz , Alexander A. Schekochihin

Near-wall turbulent velocities in turbulent channel flows are decomposed into small-scale and large-scale components at $y^+<100$ by improving the predictive inner-outer model of Baars et al. [Phys. Rev. Fluids 1, 054406 (2016)], where…

Fluid Dynamics · Physics 2021-04-16 Limin Wang , Ruifeng Hu , Xiaojing Zheng

Numerical MHD simulations play increasingly important role for understanding mechanisms of stellar magnetism. We present simulations of convection and dynamos in density-stratified rotating spherical fluid shells. We employ a new 3D…

Solar and Stellar Astrophysics · Physics 2015-09-03 Radostin D. Simitev , Alexander G. Kosovichev , Friedrich H. Busse

We quantify possible differences between turbulent dynamo action in the Sun and the dynamo action studied in idealized simulations. For this purpose we compare Fourier-space shell-to-shell energy transfer rates of three incrementally more…

Solar and Stellar Astrophysics · Physics 2011-07-08 R. Moll , J. Pietarila Graham , J. Pratt , R. H. Cameron , W. -C. Müller , M. Schüssler

We consider small oscillations of micro-particles and gaseous bubbles in viscous fluid around equilibrium states under the action of a sinusoidal external force. Exact solutions to the governing integro-differential equations containing…

Fluid Dynamics · Physics 2018-02-15 Yury A. Stepanyants , Hassan K. Hassan

The role of turbulence in current generation and self-excitation of magnetic fields has been studied in the geometry of a mechanically driven, spherical dynamo experiment, using a three dimensional numerical computation. A simple impeller…

Plasma Physics · Physics 2009-11-11 R. A. Bayliss , C. B. Forest , M. D. Nornberg , E. J. Spence , P. W. Terry

Weakly-collisional plasmas, such as the solar wind or the intra-cluster medium (ICM) of galaxy clusters, evolve in the presence of dynamically strong magnetic fields. The turbulent dynamo can amplify magnetic fields to such levels by…

Astrophysics of Galaxies · Physics 2025-02-11 Radhika Achikanath Chirakkara , Christoph Federrath , Amit Seta

Classically, large-scale forced turbulence is characterized by a transfer of energy from large to small scales via nonlinear interactions. We have investigated the changes in this energy transfer process in broad-band forced turbulence…

Fluid Dynamics · Physics 2009-11-11 A. K. Kuczaj , B. J. Geurts , W. D. McComb