Three-dimensional Visualization of Cosmological and Galaxy Formation Simulations

AbstractOur understanding of the structuring of the Universe from large-scale cosmological structures down to the formation of galaxies now largely benefits from numerical simulations. The RAMSES code, relying on the Adaptive Mesh Refinement technique, is used to perform massively parallel simulations at multiple scales. The interactive, immersive, three-dimensional visualization of such complex simulations is a challenge that is addressed using the SDvision software package. Several rendering techniques are available, including ray-casting and isosurface reconstruction, to explore the simulated volumes at various resolution levels and construct temporal sequences. These techniques are illustrated in the context of different classes of simulations. We first report on the visualization of the HORIZON Galaxy Formation Simulation at MareNostrum, a cosmological simulation with detailed physics at work in the galaxy formation process. We then carry on in the context of an intermediate zoom simulation leading to the formation of a Milky-Way like galaxy. Finally, we present a variety of simulations of interacting galaxies, including a case-study of the Antennae Galaxies interaction.

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EDGE: a new approach to suppressing numerical diffusion in adaptive mesh simulations of galaxy formation

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3645 ◽

2020 ◽

Vol 501 (2) ◽

pp. 1755-1765

Author(s):

Andrew Pontzen ◽

Martin P Rey ◽

Corentin Cadiou ◽

Oscar Agertz ◽

Romain Teyssier ◽

...

Keyword(s):

Star Formation ◽

Galaxy Formation ◽

Adaptive Mesh Refinement ◽

Large Scale ◽

Initial Conditions ◽

Dwarf Galaxy ◽

High Redshift ◽

Morphological Structure ◽

Adaptive Mesh ◽

Numerical Diffusion

ABSTRACT We introduce a new method to mitigate numerical diffusion in adaptive mesh refinement (AMR) simulations of cosmological galaxy formation, and study its impact on a simulated dwarf galaxy as part of the ‘EDGE’ project. The target galaxy has a maximum circular velocity of $21\, \mathrm{km}\, \mathrm{s}^{-1}$ but evolves in a region that is moving at up to $90\, \mathrm{km}\, \mathrm{s}^{-1}$ relative to the hydrodynamic grid. In the absence of any mitigation, diffusion softens the filaments feeding our galaxy. As a result, gas is unphysically held in the circumgalactic medium around the galaxy for $320\, \mathrm{Myr}$, delaying the onset of star formation until cooling and collapse eventually triggers an initial starburst at z = 9. Using genetic modification, we produce ‘velocity-zeroed’ initial conditions in which the grid-relative streaming is strongly suppressed; by design, the change does not significantly modify the large-scale structure or dark matter accretion history. The resulting simulation recovers a more physical, gradual onset of star formation starting at z = 17. While the final stellar masses are nearly consistent ($4.8 \times 10^6\, \mathrm{M}_{\odot }$ and $4.4\times 10^6\, \mathrm{M}_{\odot }$ for unmodified and velocity-zeroed, respectively), the dynamical and morphological structure of the z = 0 dwarf galaxies are markedly different due to the contrasting histories. Our approach to diffusion suppression is suitable for any AMR zoom cosmological galaxy formation simulations, and is especially recommended for those of small galaxies at high redshift.

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High-Resolution Numerical Simulation and Analysis of Mach Reflection Structures in Detonation Waves in Low-Pressure H2–O2–Ar Mixtures: A Summary of Results Obtained with the Adaptive Mesh Refinement Framework AMROC

Journal of Combustion ◽

10.1155/2011/738969 ◽

2011 ◽

Vol 2011 ◽

pp. 1-18 ◽

Cited By ~ 34

Author(s):

Ralf Deiterding

Keyword(s):

Numerical Simulation ◽

Adaptive Mesh Refinement ◽

Large Scale ◽

Mach Reflection ◽

Adaptive Mesh ◽

Low Pressure ◽

Detonation Waves ◽

Parallel Simulations ◽

Wide Range ◽

Complex Boundaries

Numerical simulation can be key to the understanding of the multidimensional nature of transient detonation waves. However, the accurate approximation of realistic detonations is demanding as a wide range of scales needs to be resolved. This paper describes a successful solution strategy that utilizes logically rectangular dynamically adaptive meshes. The hydrodynamic transport scheme and the treatment of the nonequilibrium reaction terms are sketched. A ghost fluid approach is integrated into the method to allow for embedded geometrically complex boundaries. Large-scale parallel simulations of unstable detonation structures of Chapman-Jouguet detonations in low-pressure hydrogen-oxygen-argon mixtures demonstrate the efficiency of the described techniques in practice. In particular, computations of regular cellular structures in two and three space dimensions and their development under transient conditions, that is, under diffraction and for propagation through bends are presented. Some of the observed patterns are classified by shock polar analysis, and a diagram of the transition boundaries between possible Mach reflection structures is constructed.

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High-Resolution Three-Dimensional MHD Simulations of Plasmoid Formation in Solar Flares

10.5194/egusphere-egu2020-10039 ◽

2020 ◽

Author(s):

Joel Dahlin ◽

Spiro Antiochos ◽

C. Richard DeVore

Keyword(s):

Current Sheet ◽

Adaptive Mesh Refinement ◽

Large Scale ◽

Magnetic Energy ◽

Three Dimensional ◽

Adaptive Mesh ◽

Dimensional Structure ◽

Small Scale ◽

Ample Evidence ◽

Current Sheets

In highly conducting plasmas, reconnecting current sheets are often unstable to the generation of plasmoids, small-scale magnetic structures that play an important role in facilitating the rapid release of magnetic energy and channeling that energy into accelerated particles. There is ample evidence for plasmoids throughout the heliosphere, from in situ observations of flux ropes in the solar wind and planetary magnetospheres to remote-sensing imaging of plasma &#8216;blobs&#8217; associated with explosive solar activity such as eruptive flares and coronal jets. Accurate models for plasmoid formation and dynamics must capture the large-scale self-organization responsible for forming the reconnecting current sheet. However, due to the computational difficulty inherent in the vast separation between the global and current sheet scales, previous numerical studies have typically explored configurations with either reduced dimensionality or pre-formed current sheets. We present new three-dimensional MHD studies of an eruptive flare in which the formation of the current sheet and subsequent reconnection and plasmoid formation are captured within a single simulation. We employ Adaptive Mesh Refinement (AMR) to selectively resolve fine-scale current sheet dynamics. Reconnection in the flare current sheet generates many plasmoids that exhibit highly complex, three-dimensional structure. We show how plasmoid formation and dynamics evolve through the course of the flare, especially in response to the weakening of the reconnection &#8220;guide field&#8221; linked to the global reduction of magnetic shear. We discuss implications of our results for particle acceleration and transport in eruptive flares as well as for observations by Parker Solar Probe and the forthcoming Solar Orbiter.

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Turbulent structure and star formation in a stratified, supernova-driven, interstellar medium

Proceedings of the International Astronomical Union ◽

10.1017/s174392130700172x ◽

2006 ◽

Vol 2 (S237) ◽

pp. 358-362

Author(s):

M. K. Ryan Joung ◽

Mordecai-Mark Mac Low

Keyword(s):

Star Formation ◽

Interstellar Medium ◽

Adaptive Mesh Refinement ◽

Formation Rate ◽

Three Dimensional ◽

Adaptive Mesh ◽

Mass Function ◽

Initial Mass Function ◽

Interstellar Turbulence ◽

Self Gravity

AbstractWe report on a study of interstellar turbulence driven by both correlated and isolated supernova explosions. We use three-dimensional hydrodynamic models of a vertically stratified interstellar medium run with the adaptive mesh refinement code Flash at a maximum resolution of 2 pc, with a grid size of 0.5 × 0.5 × 10 kpc. Cold dense clouds form even in the absence of self-gravity due to the collective action of thermal instability and supersonic turbulence. Studying these clouds, we show that it can be misleading to predict physical properties such as the star formation rate or the stellar initial mass function using numerical simulations that do not include self-gravity of the gas. Even if all the gas in turbulently Jeans unstable regions in our simulation is assumed to collapse and form stars in local freefall times, the resulting total collapse rate is significantly lower than the value consistent with the input supernova rate. The amount of mass available for collapse depends on scale, suggesting a simple translation from the density PDF to the stellar IMF may be questionable. Even though the supernova-driven turbulence does produce compressed clouds, it also opposes global collapse. The net effect of supernova-driven turbulence is to inhibit star formation globally by decreasing the amount of mass unstable to gravitational collapse.

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Cosmological simulations of low-mass galaxies: some potential issues

Proceedings of the International Astronomical Union ◽

10.1017/s1743921311000883 ◽

2010 ◽

Vol 6 (S270) ◽

pp. 503-506

Author(s):

Pedro Colín ◽

Vladimir Avila-Reese ◽

Octavio Valenzuela

Keyword(s):

Star Formation ◽

Adaptive Mesh Refinement ◽

Mass Fraction ◽

Star Formation Rate ◽

Formation Rate ◽

Mesh Refinement ◽

Adaptive Mesh ◽

Stellar Mass ◽

The Galaxy ◽

Low Mass

AbstractCosmological Adaptive Mesh Refinement simulations are used to study the specific star formation rate (sSFR=SSF/Ms) history and the stellar mass fraction, fs=Ms/MT, of small galaxies, total masses MT between few × 1010 M⊙ to few ×1011 M⊙. Our results are compared with recent observational inferences that show the so-called “downsizing in sSFR” phenomenon: the less massive the galaxy, the higher on average is its sSFR, a trend seen at least since z ~ 1. The simulations are not able to reproduce this phenomenon, in particular the high inferred values of sSFR, as well as the low values of fs constrained from observations. The effects of resolution and sub-grid physics on the SFR and fs of galaxies are discussed.

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Numerical simulations and analysis of the turbulent flow field in a practical gas turbine engine combustor

Proceedings of the Institution of Mechanical Engineers Part A Journal of Power and Energy ◽

10.1177/09576509211063255 ◽

2021 ◽

pp. 095765092110632

Author(s):

Veeraraghava R Hasti ◽

Prithwish Kundu ◽

Sibendu Som ◽

Jay P Gore

Keyword(s):

Flow Field ◽

Turbulent Flow ◽

Numerical Simulations ◽

Gas Turbine ◽

Adaptive Mesh Refinement ◽

Three Dimensional ◽

Adaptive Mesh ◽

Turbulent Structures ◽

Cut Cell ◽

Turbulent Flow Field

The turbulent flow field in a practical gas turbine combustor is very complex because of the interactions between various flows resulting from components like multiple types of swirlers, dilution holes, and liner effusion cooling holes. Numerical simulations of flows in such complex combustor configurations are challenging. The challenges result from (a) the complexities of the interfaces between multiple three-dimensional shear layers, (b) the need for proper treatment of a large number of tiny effusion holes with multiple angles, and (c) the requirements for fast turnaround times in support of engineering design optimization. Both the Reynolds averaged Navier–Stokes simulation (RANS) and the large eddy simulation (LES) for the practical combustor geometry are considered. An autonomous meshing using the cut-cell Cartesian method and adaptive mesh refinement (AMR) is demonstrated for the first time to simulate the flow in a practical combustor geometry. The numerical studies include a set of computations of flows under a prescribed pressure drop across the passage of interest and another set of computations with all passages open with a specified total flow rate at the plenum inlet and the pressure at the exit. For both sets, the results of the RANS and the LES flow computations agree with each other and with the corresponding measurements. The results from the high-resolution LES simulations are utilized to gain fundamental insights into the complex turbulent flow field by examining the profiles of the velocity, the vorticity, and the turbulent kinetic energy. The dynamics of the turbulent structures are well captured in the results of the LES simulations.

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Hydrodynamical Adaptive Mesh Refinement Simulations of Disk Galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s1743921308027956 ◽

2008 ◽

Vol 4 (S254) ◽

pp. 445-452

Author(s):

Brad K. Gibson ◽

Stéphanie Courty ◽

Patricia Sánchez-Blázquez ◽

Romain Teyssier ◽

Elisa L. House ◽

...

Keyword(s):

Galaxy Formation ◽

Adaptive Mesh Refinement ◽

Mesh Refinement ◽

Adaptive Mesh ◽

Disk Galaxies ◽

Particle Hydrodynamics ◽

Smoothed Particle ◽

Temporal And Spatial ◽

Compare And Contrast

AbstractTo date, fully cosmological hydrodynamic disk simulations to redshift zero have only been undertaken with particle-based codes, such as GADGET, Gasoline, or GCD+. In light of the (supposed) limitations of traditional implementations of smoothed particle hydrodynamics (SPH), or at the very least, their respective idiosyncrasies, it is important to explore complementary approaches to the SPH paradigm to galaxy formation. We present the first high-resolution cosmological disk simulations to redshift zero using an adaptive mesh refinement (AMR)-based hydrodynamical code, in this case, RAMSES. We analyse the temporal and spatial evolution of the simulated stellar disks' vertical heating, velocity ellipsoids, stellar populations, vertical and radial abundance gradients (gas and stars), assembly/infall histories, warps/lopsideness, disk edges/truncations (gas and stars), ISM physics implementations, and compare and contrast these properties with our sample of cosmological SPH disks, generated with GCD+. These preliminary results are the first in our long-term Galactic Archaeology Simulation program.

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Development of an Object-Oriented Program With Adaptive Mesh Refinement for Heat Transfer Simulations

ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference, Volume 1 ◽

10.1115/ht2007-32897 ◽

2007 ◽

Author(s):

Jianhu Nie ◽

David A. Hopkins ◽

Yitung Chen ◽

Hsuan-Tsung Hsieh

Keyword(s):

Heat Transfer ◽

Adaptive Mesh Refinement ◽

Large Scale ◽

Mesh Refinement ◽

Object Oriented ◽

Adaptive Mesh ◽

Time Cost ◽

Test Bed ◽

Element Analysis ◽

Cpu Time

A 2D/3D object-oriented program with h-type adaptive mesh refinement method is developed for finite element analysis of the multi-physics applications including heat transfer. A framework with some basic classes that enable the code to be built accordingly to the type of problem to be solved is proposed. The program consists of different modules and classes, which ease code development for large-scale complex systems, code extension and program maintenance. The developed program can be used as a “test-bed” program for testing new analysis techniques and algorithms with high extensibility and flexibility. The overall mesh refinement causes the CPU time cost to greatly increase as the mesh is refined. However, the CPU time cost does not increase very much with the increase of the level of h-adaptive mesh refinement. The CPU time cost can be saved by up to 90%, especially for the simulated system with a large number of elements and nodes.

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Simulations of the star-forming molecular gas in an interacting M51-like galaxy

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz3600 ◽

2020 ◽

Vol 492 (2) ◽

pp. 2973-2995 ◽

Cited By ~ 11

Author(s):

Robin G Tress ◽

Rowan J Smith ◽

Mattia C Sormani ◽

Simon C O Glover ◽

Ralf S Klessen ◽

...

Keyword(s):

Star Formation ◽

Large Scale ◽

Formation Rate ◽

Three Dimensional ◽

Molecular Gas ◽

Secondary Importance ◽

Star Forming ◽

The Galaxy ◽

Cold Star ◽

Self Gravity

ABSTRACT We present here the first of a series of papers aimed at better understanding the evolution and properties of giant molecular clouds (GMCs) in a galactic context. We perform high-resolution, three-dimensional arepo simulations of an interacting galaxy inspired by the well-observed M51 galaxy. Our fiducial simulations include a non-equilibrium, time-dependent, chemical network that follows the evolution of atomic and molecular hydrogen as well as carbon and oxygen self-consistently. Our calculations also treat gas self-gravity and subsequent star formation (described by sink particles), and coupled supernova feedback. In the densest parts of the simulated interstellar medium (ISM), we reach sub-parsec resolution, granting us the ability to resolve individual GMCs and their formation and destruction self-consistently throughout the galaxy. In this initial work, we focus on the general properties of the ISM with a particular focus on the cold star-forming gas. We discuss the role of the interaction with the companion galaxy in generating cold molecular gas and controlling stellar birth. We find that while the interaction drives large-scale gas flows and induces spiral arms in the galaxy, it is of secondary importance in determining gas fractions in the different ISM phases and the overall star formation rate. The behaviour of the gas on small GMC scales instead is mostly controlled by the self-regulating property of the ISM driven by coupled feedback.

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CFD simulations of tsunamis from large scale propagation up to local coastal impacts

10.5194/egusphere-egu2020-3006 ◽

2020 ◽

Author(s):

Richard Marcer ◽

Camille Journeau ◽

Kévin Pons

Keyword(s):

Adaptive Mesh Refinement ◽

Large Scale ◽

Adaptive Mesh ◽

Navier Stokes ◽

Water Volume ◽

Tsunami Propagation ◽

Tsunami Modelling ◽

Tsunami Waves ◽

In Situ Data ◽

Run Up

This work has been performed within the framework of the TANDEM project (Tsunamis in northern AtlaNtic: Definition of Effects by Modelling) which is dedicated to the appraisal of coastal effects due to tsunami waves on the French coastlines. One of the identified objectives of TANDEM consisted in designing, adapting and validating numerical codes for tsunami hazard assessment, addressing the various stages of a tsunami event: generation, propagation, run-up and coastal inundation.PRINCIPIA has been working on the development and qualification of two in-house CFD software&#8217;s: a 2D Saint-Venant model (often called NLSW for Non-Linear Shallow Water) using an Adaptive Mesh Refinement (AMR) for simulation of large scale tsunami propagation from the source up to coastal scale, and a 3D Navier-Stokes model dedicated to tsunami coastal impact modelling.An overview of the results obtained with both codes aiming at being applicable to tsunami modelling, is presented. The validation process has been done on several academic test cases having experimental data for comparisons, as the breaking of a solitary wave on a reef, the generation of a long wave induced by a vertical bloc (massive cliffs, ice bodies) falling down an underlying water volume, the tsunami generation due to a submarine landslide and the tsunami impact on a coastal city.A real case simulation is concerned as well, the devastating 2011 Tohoku event which is compared with in-situ data.The work was supported by the Tandem project in the frame of French PIA grant ANR-11-RSNR-00023.

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