EvoL: the new Padova Tree-SPH parallel code for cosmological simulations

Merlin, E.; Buonomo, U.; Piovan, L.; Chiosi, C.

doi:10.1051/0004-6361/200913514

Cited by 37 publications

(67 citation statements)

References 65 publications

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“…This time step limiter is important when large differences in temperature occur between the pre-and post-shock media (Saitoh & Makino 2009;Merlin et al 2010). It is not critical in our case, as the net heating of the ISM caused by SNe explosions never exceeds a factor of 20.…”

Section: Feedbackmentioning

confidence: 95%

The dynamical and chemical evolution of dwarf spheroidal galaxies with GEAR

Revaz

Jablonka

2012

A&A

134

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We present the fully parallel chemo-dynamical Tree/SPH code GEAR, which allows us to perform high resolution simulations with detailed chemical diagnostics. Starting from the public version of Gadget-2, we included the complex treatment of the baryon physics: gas cooling, star formation law, chemical evolution, and supernova feedback. We qualified the performances of GEAR in the case of dwarf spheroidal galaxies (dSphs) galaxies. Our code GEAR conserves the total energy budget of the systems to better than 5% over 14 Gyr and provides an excellent convergence of the results with numerical resolution. We showed that models of dSphs in a static Euclidean space, where the expansion of the universe is neglected are valid. In addition, we tackled some existing open questions in the field, such as the stellar mass fraction of dSphs and its link to the predicted dark matter halo mass function, the effect of supernova feedback, the spatial distribution of the stellar populations, and the origin of the diversity in star formation histories and chemical abundance patterns. Strong supernova-driven winds seem incompatible with the observed metallicities and luminosities. Despite newly formed stars being preferentially found in the galaxy central parts, turbulent motions in the gas can quickly erase any metallicity gradient. The diversity in properties of dSph are related to a range of total masses, as well as a range of dispersion in the central densities, which is also seen in the halos emerging from a ΛCDM cosmogony.

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Section: Feedbackmentioning

confidence: 95%

The dynamical and chemical evolution of dwarf spheroidal galaxies with GEAR

Revaz

Jablonka

2012

A&A

134

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“…The ability of the new AC formulation of SPH to follow the development of KH instabilities using this expression for the signal velocity was verified in a number of tests (Price 2008;Valcke et al 2010;Merlin et al 2010). However, the disadvantage of using the signal speed (24) is that it cannot be applied when self-gravity is considered because in that case a pressure gradient is present at hydrostatic equilibrium.…”

Section: Artificial Conductivitymentioning

confidence: 99%

Hydrodynamic capabilities of an SPH code incorporating an artificial conductivity term with a gravity-based signal velocity

Valdarnini

2012

A&A

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This paper investigates the hydrodynamic performances of an smoothed particle hydrodynamics (SPH) code incorporating an artificial heat conductivity term in which the adopted signal velocity is applicable when gravity is present. To this end, we analyze results from simulations produced using a suite of standard hydrodynamical test problems. In accordance with previous findings, we show that the performances of SPH in describing the development of Kelvin-Helmholtz instabilities depend strongly on both the consistency of the initial condition set-up and the leading error in the momentum equation due to incomplete kernel sampling. In contrast, the presence of artificial conductivity does not significantly affect the results. An error and stability analysis shows that the quartic B-spline kernel (M 5 ) possesses very good stability properties and so we propose its use with a large neighbor number, between ∼50 (2D) to ∼100 (3D), to improve convergence in simulation results without being affected by the so-called clumping instability. Moreover, the results of the Sod shock tube demonstrate that to obtain simulation profiles in accord with the analytic solution, for simulations employing kernels with a non-zero first derivative at the origin, it is necessary to use a much larger number of neighbors than in the case of the M 5 runs. Our SPH simulations of the blob test show that in order to achieve blob disruption it is necessary to include an artificial conductivity term. However, we find that in the regime of strong supersonic flows an appropriate limiting condition, which depends on the Prandtl number, must be imposed on the artificial conductivity SPH coefficients in order to avoid an unphysical amount of heat diffusion. Our results from hydrodynamic simulations that include self-gravity show profiles of hydrodynamic variables that are in much better agreement with those produced using mesh-based codes. In particular, the final levels of core entropies in cosmological simulations of galaxy clusters are consistent with those found using AMR codes. This demonstrates that the proposed diffusion scheme is capable of mimicking the process of entropy mixing that is produced during structure formation because of the diffusion caused by turbulence. Finally, the results of our Rayleigh-Taylor instability test demonstrate that in the regime of very subsonic flows the code still has several difficulties in the treatment of hydrodynamic instabilities. These problems are intrinsic to the way in which standard SPH gradients are calculated and not to the implementation of the artificial conductivity term. To overcome these difficulties, several numerical schemes have been proposed that, if coupled with the SPH implementation presented in this paper, could solve the issues that have recently been addressed in investigating SPH performances to model subsonic turbulence.

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“…Once the ANNs are instructed to reproduce the (robo) results as a function of the parameters, they should replace robo in the NB-TSPH simulator of galaxies. In our case the NB-TSPH model is EvoL by Merlin & Chiosi (2006 and Merlin et al (2010). The use of ANNs can greatly improve upon this point of difficulty.…”

Section: Introductionmentioning

confidence: 94%

ROBO: a model and a code for studying the interstellar medium

Krstić

Merlin

Buonomo

et al. 2011

A&A

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We present robo, a model and its companion code for the study of the interstellar medium (ISM). The aim is to provide an accurate description of the physical evolution of the ISM and to set the ground for an ancillary tool to be inserted in NBody-Tree-SPH (NB-TSPH) simulations of large-scale structures in the cosmological context or of the formation and evolution of individual galaxies. The ISM model consists of gas and dust. The gas chemical composition is regulated by a network of reactions that includes a large number of species (hydrogen and deuterium-based molecules, helium, and metals). New reaction rates for the charge transfer in H + and H 2 collisions are presented. The dust contains the standard mixture of carbonaceous grains (graphite grains and PAHs) and silicates. In our model dust are formed and destroyed by several processes. The model accurately treats the cooling process, based on several physical mechanisms, and cooling functions recently reported in the literature. The model is applied to a wide range of the input parameters, and the results for important quantities describing the physical state of the gas and dust are presented. The results are organized in a database suited to the artificial neural networks (ANNs). Once trained, the ANNs yield the same results obtained by ROBO with great accuracy. We plan to develop ANNs suitably tailored for applications to NB-TSPH simulations of cosmological structures and/or galaxies.

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EvoL: the new Padova Tree-SPH parallel code for cosmological simulations

Cited by 37 publications

References 65 publications

The dynamical and chemical evolution of dwarf spheroidal galaxies with GEAR

The dynamical and chemical evolution of dwarf spheroidal galaxies with GEAR

Hydrodynamic capabilities of an SPH code incorporating an artificial conductivity term with a gravity-based signal velocity

ROBO: a model and a code for studying the interstellar medium

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