[Commits] [svn:einsteintoolkit] Paper_EinsteinToolkit_2010/ (Rev. 174)

cott at tapir.caltech.edu cott at tapir.caltech.edu
Mon Nov 7 20:57:52 CST 2011


User: cott
Date: 2011/11/07 08:57 PM

Modified:
 /
  ET.tex

Log:
 * new version of the conclusions and future work

File Changes:

Directory: /
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File [modified]: ET.tex
Delta lines: +93 -52
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--- ET.tex	2011-11-07 20:06:30 UTC (rev 173)
+++ ET.tex	2011-11-08 02:57:52 UTC (rev 174)
@@ -85,10 +85,10 @@
 Eloisa Bentivegna $^3$,
 Tanja Bode $^4$,
 Peter Diener $^1$,
-Roland Haas $^5$,
+Roland Haas $^{5,4}$,
 Ian Hinder $^3$,
 Bruno C. Mundim $^2$,
-Christian D. Ott $^5$,
+Christian D. Ott $^{5,1}$,
 Erik Schnetter $^{6,7,1}$,
 Gabrielle Allen $^1$,
 Manuela Campanelli $^2$
@@ -99,7 +99,7 @@
 \address{$^2$ Center for Computational Relativity and Gravitation, School of Mathematical Sciences, Rochester Institute of Technology, Rochester, NY, USA}
 \address{$^3$ AEI \todo{complete}}
 \address{$^4$ GTech \todo{complete}}
-\address{$^5$ Caltech \todo{complete}}
+\address{$^5$ TAPIR, California Institute of Technology, Pasadena, CA, USA}
 \address{$^6$ Perimeter Institute for Theoretical Physics, Waterloo,
   ON, Canada}
 \address{$^7$ Department of Physics, University of Guelph, Guelph, ON,
@@ -2870,61 +2870,102 @@
 \end{figure}
 
 
-\section{Future Work}
-In this paper we illustrated the state of the ``Einstein Toolkit'' release ``Curie'',
-a collection of freely available and easy to use computational codes
-for numerical relativity. However, there is room for improvement on both
-the underlying infrastructure and the included physics.
+\section{Conclusion and Future Work}
+In this article, we described the Einstein Toolkit, a collection
+of freely available and easy to use computational codes for numerical
+relativity and relativistic astrophysics. The code details and example
+results present in this article represent the state of the Einstein
+Toolkit in its release ET\_2011\_05 ``Curie,'' released on April 21,
+2011. 
 
-One of the desirable additions of physics is a proper treatment of
-radiation, in particular neutrinos. Another desirable addition would be some
-approximation of emission of electro-magnetic waves. Radiation transport is,
-even compared to the full GRMHD problem, computationally very expensive,
-especially in three dimensions. Several members of the CIGR team are involved
-in the NSF project PetaCactus, which aims to explore these possibilities.
+What was presented here is but a snapshot of the Einstein Toolkit's
+ongoing development whose ultimate goal it is to provide an
+open-source set of robust baseline codes to realistically and
+reproducibly model the whole spectrum of relativistic astrophysical
+phenomena including, but not limited to, isolated black holes and
+neutron stars, binary black hole coalescence in vacuum and gaseous
+environs, double neutron star and neutron star -- black hole mergers,
+core-collapse supernovae, and gamma-ray bursts.
 
-Besides new additions, existing techniques require to be improved. One such
-example is the improvement of current wave extraction techniques within the
-Einstein Toolkit to include Cauchy characteristic wave extraction techniques,
-as recently studied in~\cite{???}.  \todo{citation}  The authors of these research codes
-agreed to make their work available to the whole community within
-the Einstein toolkit, which happened in the recently released version ``Maxwell'',
-but which is not described here.
+For this, much future work towards including proper treatments of
+magnetic fields, more complex equations of state, nuclear reactions,
+neutrinos, and photons will be necessary and will need to be matched
+by improvements in infrastructure (e.g., more flexible AMR on general
+grids) and computing hardware for the required fully coupled 3D,
+multi-scale, multi-physics simulations to become reality.
 
-A second example for an improvement of an existing method is extending the
-current implementation of ideal magnetohydrodynamics to the case of non-zero
-resistivity. Such implementations exist
-and are described in the literature~\cite{???} \todo{cite}, but none have been provided freely
-within the Einstein Toolkit until the recently released ``Maxwell'' version.
-Resistive MHD is important for a number of astrophysical scenarios, one of
-which is the merger of two magnetized NSs, a candidate for short gamma-ray
-bursts.
-\todo{reword - make clear that we describe Curie}
+%%% One of the desirable additions of physics is a proper treatment of
+%%% radiation, in particular neutrinos. Another desirable addition would be some
+%%% approximation of emission of electro-magnetic waves. Radiation transport is,
+%%% even compared to the full GRMHD problem, computationally very expensive,
+%%% especially in three dimensions. 
 
-Yet another important goal is to increase the scalability of the {\tt Carpet} AMR
-infrastructure. It has been shown that good scaling is limited to less than
-a few thousand processes, for some of the most used simulation scenarios.
-In this case, work is already in progress to eliminate this bottle-neck.
-On the other hand, a production simulation is typically composed from a large
-number of components, and all of them have to scale well to achieve overall
-good performance. This is not an easy problem, as most of the module authors
-are neither computer scientists nor had they extensive training in parallel
-development and profiling techniques. Close collaboration with such experts
-has been shown to be very fruitful in the past and is definitely also planned
-for the foreseeable future.
+%%% CDO: It is not appropriate to mention a grant like PetaCactus as an ``NSF Project''.
+%%% Please leave this out.
+%%% Several members of the CIGR team are involved
+%%% in the NSF project PetaCactus, which aims to explore these possibilities.
 
+Besides new additions of physics modules, existing techniques require
+improvement. One example is the need for the gauge invariant
+extraction of gravitational waves from simulation spacetimes as realized
+by the Cauche Characteristic Extraction (CCE) technique recently studied
+in \cite{Babiuc:11,Reisswig:2010cd,Reisswig:2011a}.  The authors of one such
+CCE code \cite{Babiuc:11} have agreed to make their work available to the
+whole community by integrating their CCE routines into the Einstein Tookit
+release 2011\_11 ``Maxwell,'' which will be described elsewhere.
+
+A second example for a much needed improvement of an existing method
+is to transition to cell-centered AMR for GR hydrodynamic simulations,
+which would allow for exact flux conservation across AMR interfaces
+via a refluxing step that adjusts coarse and/or fine grid fluxes for
+consistency (e.g., \cite{Berger:1984zza}). This is also a prerequisite
+for the constrained transport method \cite{Toth:00} for ensuring the
+divergence-free condition for the magnetic field in a future
+implementation of GRMHD within the Einstein Toolkit. Work towards
+cell-centered AMR, refluxing, and GRMHD is underway and will be
+reported in a future publication.
+
+
+%%% CDO: We have not even talked about the current MHD implementation,
+%%% how can we talk about its improvement?
+%%%
+%%% A second example for an improvement of an existing method is extending the
+%%% current implementation of ideal magnetohydrodynamics to the case of non-zero
+%%% resistivity. Such implementations exist
+%%% and are described in the literature~\cite{???} \todo{cite}, but none have been provided freely
+%%% within the Einstein Toolkit until the recently released ``Maxwell'' version.
+%%% Resistive MHD is important for a number of astrophysical scenarios, one of
+%%% which is the merger of two magnetized NSs, a candidate for short gamma-ray
+%%% bursts.
+%%% \todo{reword - make clear that we describe Curie}
+
+Yet another important goal is to increase the scalability of the {\tt
+  Carpet} AMR infrastructure. As we have shown, good scaling is
+limited to only a few thousand processes for some of the most used
+simulation scenarios.  Work is in progress to eliminate this
+bottle-neck.  On the other hand, a production simulation is typically
+composed of a large number of components, and even analysis and I/O
+routines have to scale well to achieve overall good performance. This
+is a highly non-trivial problem, since most Einstein Toolkit physics
+module authors are neither computer scientists nor have they had
+extensive training in parallel development and profiling
+techniques. Close collaboration with experts in these topics has been
+fruitful in the past and will be absolutely necessary for the
+optimization of Einstein Toolkit codes for execution on the upcoming
+generation of true petascale supercomputers on which typical compute jobs
+are expected to be running on 100,000 and more compute cores.
+
 \section*{Acknowledgments\pages{0.5 All}}
-\todo{Frank, ADD}
-The Einstein Toolkit is directly supported by the National Science Foundation
-under the grant numbers 0903973/0903782/0904015 (CIGR\@).
-Related grants contribute directly and indirectly to the success of CIGR,
-including NSF OCI 0721915 ``Alpaca'', NSF OCI 0725070
-``Blue Waters'', NSF OCI 0905046 ``PetaCactus'', and
-NSF OCI 0941653 ``PRAC''. Results presented
-in this article were obtained through computations on the Louisiana Optical
-Network Initiative under allocation loni\_cactus05 and loni\_numrel06, as well
-as on the NSF Teragrid under allocation TG-MCA02N014, DOE repository m152,
-HLRB at the LRZ, and Compute Canada project cfz-411-aa.
+\todo{Frank, ADD} The Einstein Toolkit is directly supported by the
+National Science Foundation under the grant numbers
+0903973/0903782/0904015 (CIGR\@).  Related grants contribute directly
+and indirectly to the success of CIGR, including NSF OCI-0721915, NSF
+OCI-0725070, NSF OCI-0905046, and NSF OCI 0941653, and NSF
+AST-0855535. Results presented in this article were obtained through
+computations on the Louisiana Optical Network Initiative under
+allocation loni\_cactus05 and loni\_numrel06, as well as on the NSF
+Teragrid under allocation TG-MCA02N014, DOE repository m152, HLRB at
+the LRZ, and Compute Canada project cfz-411-aa.
 
 \section*{References}
 



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