@article{hopkinsGIZMONewClass2015, archivePrefix = {arXiv}, eprinttype = {arxiv}, eprint = {1409.7395}, title = {{{GIZMO}}: {{A New Class}} of {{Accurate}}, {{Mesh}}-{{Free Hydrodynamic Simulation Methods}}}, volume = {450}, issn = {0035-8711, 1365-2966}, shorttitle = {{{GIZMO}}}, abstract = {We present two new Lagrangian methods for hydrodynamics, in a systematic comparison with moving-mesh, SPH, and stationary (non-moving) grid methods. The new methods are designed to simultaneously capture advantages of both smoothed-particle hydrodynamics (SPH) and grid-based/adaptive mesh refinement (AMR) schemes. They are based on a kernel discretization of the volume coupled to a high-order matrix gradient estimator and a Riemann solver acting over the volume 'overlap.' We implement and test a parallel, second-order version of the method with self-gravity \& cosmological integration, in the code GIZMO: this maintains exact mass, energy and momentum conservation; exhibits superior angular momentum conservation compared to all other methods we study; does not require 'artificial diffusion' terms; and allows the fluid elements to move with the flow so resolution is automatically adaptive. We consider a large suite of test problems, and find that on all problems the new methods appear competitive with moving-mesh schemes, with some advantages (particularly in angular momentum conservation), at the cost of enhanced noise. The new methods have many advantages vs. SPH: proper convergence, good capturing of fluid-mixing instabilities, dramatically reduced 'particle noise' \& numerical viscosity, more accurate sub-sonic flow evolution, \& sharp shock-capturing. Advantages vs. non-moving meshes include: automatic adaptivity, dramatically reduced advection errors \& numerical overmixing, velocity-independent errors, accurate coupling to gravity, good angular momentum conservation and elimination of 'grid alignment' effects. We can, for example, follow hundreds of orbits of gaseous disks, while AMR and SPH methods break down in a few orbits. However, fixed meshes minimize 'grid noise.' These differences are important for a range of astrophysical problems.}, number = {1}, journal = {Monthly Notices of the Royal Astronomical Society}, doi = {10.1093/mnras/stv195}, author = {Hopkins, Philip F.}, month = jun, year = {2015}, keywords = {Astrophysics - Cosmology and Nongalactic Astrophysics,Astrophysics - Instrumentation and Methods for Astrophysics,Physics - Computational Physics,Astrophysics - Astrophysics of Galaxies,Physics - Fluid Dynamics,_tablet}, pages = {53-110}, file = {/home/mivkov/Zotero/storage/23ALA3M9/Hopkins_2015_GIZMO.pdf;/home/mivkov/Zotero/storage/SHV6QDMB/1409.html} } @article{lansonRenormalizedMeshfreeSchemes2008, title = {Renormalized {{Meshfree Schemes I}}: {{Consistency}}, {{Stability}}, and {{Hybrid Methods}} for {{Conservation Laws}}}, volume = {46}, issn = {0036-1429}, shorttitle = {Renormalized {{Meshfree Schemes I}}}, abstract = {This paper is devoted to the study of a new kind of meshfree scheme based on a new class of meshfree derivatives: the renormalized meshfree derivatives, which improve the consistency of the original weighted particle methods. The weak renormalized meshfree scheme, built from the weak formulation of general conservation laws, turns out to be \$L\^2\$ stable under some geometrical conditions on the distribution of particles and some regularity conditions of the transport field. A time discretization is then performed by analogy with finite volume methods, and the \$L\^1\$, \$L\^\textbackslash{}infty\$, and \$BV\$ stabilities of the obtained time discretized scheme are studied. From the same analogy with finite volume methods, a hybrid particle scheme is built using the Godunov method and is numerically compared to the weak renormalized scheme.}, number = {4}, journal = {SIAM J. Numer. Anal.}, doi = {10.1137/S0036142903427718}, author = {Lanson, Nathalie and Vila, Jean-Paul}, month = apr, year = {2008}, keywords = {finite volume,hybrid particle schemes,meshfree methods,nonlinear conservation law,renormalization,SPH,weak scheme,_tablet}, pages = {1912--1934}, file = {/home/mivkov/Zotero/storage/QPBH9IJ6/Lanson_Vila_2008_Renormalized Meshfree Schemes I.pdf} } @article{ivanovaCommonEnvelopeEvolution2013, archivePrefix = {arXiv}, eprinttype = {arxiv}, eprint = {1209.4302}, title = {Common {{Envelope Evolution}}: {{Where}} We Stand and How We Can Move Forward}, volume = {21}, issn = {0935-4956, 1432-0754}, shorttitle = {Common {{Envelope Evolution}}}, abstract = {This work aims to present our current best physical understanding of common-envelope evolution (CEE). We highlight areas of consensus and disagreement, and stress ideas which should point the way forward for progress in this important but long-standing and largely unconquered problem. Unusually for CEE-related work, we mostly try to avoid relying on results from population synthesis or observations, in order to avoid potentially being misled by previous misunderstandings. As far as possible we debate all the relevant issues starting from physics alone, all the way from the evolution of the binary system immediately before CEE begins to the processes which might occur just after the ejection of the envelope. In particular, we include extensive discussion about the energy sources and sinks operating in CEE, and hence examine the foundations of the standard energy formalism. Special attention is also given to comparing the results of hydrodynamic simulations from different groups and to discussing the potential effect of initial conditions on the differences in the outcomes. We compare current numerical techniques for the problem of CEE and also whether more appropriate tools could and should be produced (including new formulations of computational hydrodynamics, and attempts to include 3D processes within 1D codes). Finally we explore new ways to link CEE with observations. We compare previous simulations of CEE to the recent outburst from V1309 Sco, and discuss to what extent post-common-envelope binaries and nebulae can provide information, e.g. from binary eccentricities, which is not currently being fully exploited.}, number = {1}, journal = {The Astronomy and Astrophysics Review}, doi = {10.1007/s00159-013-0059-2}, author = {Ivanova, N. and Justham, S. and Chen, X. and De Marco, O. and Fryer, C. L. and Gaburov, E. and Ge, H. and Glebbeek, E. and Han, Z. and Li, X.-D. and Lu, G. and Marsh, T. and Podsiadlowski, Ph and Potter, A. and Soker, N. and Taam, R. and Tauris, T. M. and van den Heuvel, E. P. J. and Webbink, R. F.}, month = nov, year = {2013}, keywords = {Astrophysics - High Energy Astrophysical Phenomena,Astrophysics - Solar and Stellar Astrophysics,_tablet}, file = {/home/mivkov/Zotero/storage/V6IL3NUY/Ivanova et al_2013_Common Envelope Evolution.pdf;/home/mivkov/Zotero/storage/MMFFSMV7/1209.html} } @phdthesis{vandenbrouckeAdvancedModelsSimulating, title = {{Advanced models for simulating dwarf galaxy formation and evolution}}, language = {nl}, author = {Vandenbroucke, Bert}, year = {2016}, file = {/home/mivkov/Zotero/storage/T3UZJAWQ/Vandenbroucke - Advanced models for simulating dwarf galaxy format.pdf} }