Search results for "Adaptive Mesh Refinement"
showing 10 items of 23 documents
General Relativistic Simulations of Accretion Disks Around Tilted Kerr Black Holes
2014
We simulate the dynamics of self-gravitating accretion disks around tilted Kerr black holes (BH) in full 3D general relativity. For this purpose we employ the EinsteinToolkit, using the thorn McLachlan for the evolution of the spacetime via the BSSN formalism of the Einstein equations and the thorn GRHydro for the evolution of the hydrodynamics, using a 3D Cartesian mesh with adaptive mesh refinement. We investigate the effects of the tilt angle between the disk angular momentum and BH spin vector on the dynamics of these systems as the disk evolves in the tilted spacetime. By evolving the spacetime and matter fields, we are able to observe how both BH and disk react and evolve in the tilte…
ASOHF: a new adaptive spherical overdensity halo finder
2010
We present and test a new halo finder based on the spherical overdensity (SO) method. This new adaptive spherical overdensity halo finder (ASOHF) is able to identify dark matter haloes and their substructures (subhaloes) down to the scales allowed by the analysed simulations. The code has been especially designed for the adaptive mesh refinement cosmological codes, although it can be used as a stand-alone halo finder for N-body codes. It has been optimised for the purpose of building the merger tree of the haloes. In order to verify the viability of this new tool, we have developed a set of bed tests that allows us to estimate the performance of the finder. Finally, we apply the halo finder…
Galaxy cluster mergers
2009
We present the results of an Eulerian adaptive mesh refinement (AMR) hydrodynamical and N-body simulation in a $\Lambda$CDM cosmology. The simulation incorporates common cooling and heating processes for primordial gas. A specific halo finder has been designed and applied in order to extract a sample of galaxy clusters directly obtained from the simulation without considering any resimulating scheme. We have studied the evolutionary history of the cluster halos, and classified them into three categories depending on the merger events they have undergone: major mergers, minor mergers, and relaxed clusters. The main properties of each one of these classes and the differences among them are di…
Cosmic magnetic fields with masclet: an application to galaxy clusters
2020
We describe and test a new version of the adaptive mesh refinement (AMR) cosmological code MASCLET. The new version of the code includes all the ingredients of its previous version plus a description of the evolution of the magnetic field under the approximation of the ideal magneto-hydrodynamics (MHD). To preserve the divergence-free condition of MHD, the original divergence cleaning algorithm of Dedner et al. (2002) is implemented. We present a set of well-known 1D and 2D tests, such as several shock-tube problems, the fast rotor and the Orszag-Tang vortex. The performance of the code in all the tests is excellent with estimated median relative errors of $\nabla \cdot {\bf B}$ in the 2D t…
Unravelling cosmic velocity flows: a Helmholtz-Hodge decomposition algorithm for cosmological simulations
2021
In the context of intra-cluster medium turbulence, it is essential to be able to split the turbulent velocity field in a compressive and a solenoidal component. We describe and implement a new method for this aim, i.e., performing a Helmholtz-Hodge decomposition, in multi-grid, multi-resolution descriptions, focusing on (but not being restricted to) the outputs of AMR cosmological simulations. The method is based on solving elliptic equations for a scalar and a vector potential, from which the compressive and the solenoidal velocity fields, respectively, are derived through differentiation. These equations are addressed using a combination of Fourier (for the base grid) and iterative (for t…
A new multidimensional adaptive mesh refinement hydro + gravity cosmological code
2004
A new cosmological multidimensional hydrodynamic and N-body code based on an Adaptive Mesh Refinement scheme is described and tested. The hydro part is based on modern high-resolution shock-capturing techniques, whereas N-body approach is based on the Particle Mesh method. The code has been specifically designed for cosmological applications. Tests including shocks, strong gradients, and gravity have been considered. A cosmological test based on Santa Barbara cluster is also presented. The usefulness of the code is discussed. In particular, this powerful tool is expected to be appropriate to describe the evolution of the hot gas component located inside asymmetric cosmological structures.
Masclet: a new multidimensional AMR cosmological code
2004
A new cosmological multidimensional hydrodynamic and N-body code based on an Adaptive Mesh Refinement scheme is described and tested. The hydro part is based on modern high-resolution shock-capturing techniques, whereas N-body approach is based on a Particle Mesh method. The code has been specifically designed for cosmological applications.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html
The structure of cosmic voids in a LCDM Universe
2013
Eulerian cosmological codes are especially suited to properly describe the low density regions. This property makes this class of codes excellent tools to study the formation and evolution of cosmic voids. Following such ideas, we present the results of an Eulerian adaptive mesh refinement (AMR) hydrodynamical and N-body simulation, that contrary to the common practice, has been designed to refine the computational grid in the underdense regions of the simulated volume. Thus, the void regions are better described due to the combined effect of the Eulerian character of the numerical technique and the use of high numerical resolution from the AMR approach. To analyse the outcome of this simul…
Well-Balanced Adaptive Mesh Refinement for shallow water flows
2014
Well-balanced shock capturing (WBSC) schemes constitute nowadays the state of the art in the numerical simulation of shallow water flows. They allow to accurately represent discontinuous behavior, known to occur due to the non-linear hyperbolic nature of the shallow water system, and, at the same time, numerically maintain stationary solutions. In situations of practical interest, these schemes often need to be combined with some kind of adaptivity, in order to speed up computing times. In this paper we discuss what ingredients need to be modified in a block-structured AMR technique in order to ensure that, when combined with a WBSC scheme, the so-called 'water at rest' stationary solutions…
Highly Accurate Conservative Finite Difference Schemes and Adaptive Mesh Refinement Techniques for Hyperbolic Systems of Conservation Laws
2007
We review a conservative finite difference shock capturing scheme that has been used by our research team over the last years for the numerical simulations of complex flows [3, 6]. This scheme is based on Shu and Osher’s technique [9] for the design of highly accurate finite difference schemes obtained by flux reconstruction procedures (ENO, WENO) on Cartesian meshes and Donat-Marquina’s flux splitting [4]. We then motivate the need for mesh adaptivity to tackle realistic hydrodynamic simulations on two and three dimensions and describe some details of our Adaptive Mesh Refinement (AMR) ([2, 7]) implementation of the former finite difference scheme [1]. We finish the work with some numerica…