User: knarf Date: 2013/01/24 02:21 PM

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File [added]: index.php Delta lines: +56 -0 =================================================================== --- seminars/2013_02_04/index.php (rev 0) +++ seminars/2013_02_04/index.php 2013-01-24 20:21:12 UTC (rev 930) @@ -0,0 +1,56 @@ +<?php $title='Three-Dimensional General-Relativistic Hydrodynamic Simulations of Binary Neutron Star Coalescence and Stellar Collapse with Multipatch Grids'; +include_once($_SERVER['DOCUMENT_ROOT'].'/global/header.php');?> + +<h3>Monday, Feburary 04, 2013, 10am US central time</h3> +<p>Within the usual Einstein Toolkit weekly meeting time WebEx will be used for audio, +video and slides. The slides and recordings will later be available here. +The talk is based on this <a href="http://arxiv.org/abs/1212.1191">paper</a>. +</p> + + +<h3>Abstract</h3> +<p> +I discuss the implementation and performance of multipatch grids in the general +relativistic hydrodynamics code "GRHydro" (see http://arxiv.org/abs/1212.1191). +Multipatch methods allow one to cover the computational domain with multiple +curvi-linear grid patches that can be adapted to the problem symmetry. For +instance, rectangular Cartesian grids are useful for the region directly +covering the central source (such as a binary neutron star system), but +spherical grids are more efficient in the far-away region, e.g. the +gravitational wave zone. Combining the different grid shapes can offer +significant performance/accuracy benefits. The multipatch implementation in +GRHydro is based on overlapping grids where ghost data between patches is +exchanged via high-order Lagrange interpolation polynomials for spacetime +variables, and second-order essentially non-oscillatory (ENO) interpolation for +fluid variables that may contain shocks and other discontinuities. I describe +the changes that were introduced to make GRHydro compatible with multipatch +grids. In addition, I also briefly describe the implementation of +cell-centered adaptive mesh-refinement and refluxing, a technique of ensuring +numerical flux conservation at mesh refinement boundaries (corresponding to +conservation of mass, energy, and momentum in the absence of gravity). I +finally show the performance of the new updates to GRHydro by a number of test +problems: (perturbed) TOV star, stellar collapse, and binary neutron star +coalescence. +</p> + +<h3>Presenter: Christian Reisswig</h3> +<img src="reisswig-new-s.jpg" width="20%" align="right" alt="Christian Reisswig"> +<p> + NASA Einstein Postdoctoral Fellow in Theoretical Astrophysics at the <a + href="http://www.tapir.caltech.edu/%22%3ETheoretical Astrophysics (TAPIR) group</a> + at the <a href="http://www.caltech.edu/">California Institute of Technology</a> +<p> + +<p>Research interests: +I am interested in the modeling of gravitationally radiating sources such as +coalescing compact binaries and collapsing stellar cores using numerical +relativity. This work involves extending our understanding of the physics of +these sources, their dynamics, and their emitted gravitational wave signature. +A prime goal is the construction of template banks to be used in gravitational +wave observatories such as LIGO, Virgo and GEO600. I develop and extend +simulations based on Einstein's theory of general relativity that run on +massively parallel computers. A particular focus of my research has been on +gravitational-wave extraction techniques and binary black hole merger physics. +</p> + +<?php include_once($_SERVER['DOCUMENT_ROOT'].'/global/footer.php');?>

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File [modified]: index.php Delta lines: +12 -0 =================================================================== --- seminars/index.php 2013-01-24 18:12:04 UTC (rev 929) +++ seminars/index.php 2013-01-24 20:21:12 UTC (rev 930) @@ -6,6 +6,18 @@ location are, besides here, announced on the Einstein Toolkit mailing list. </p>

+<h3>Upcoming Seminars</h3> +<table border="1"> + <tr><th>Date</th><th>Title</th><th>Presenter</th><th>Affiliation</th><th>Slides</th></tr> + <tr> + <td>2012/02/04</td> + <td><a href="2013_02_04/">Three-Dimensional General-Relativistic Hydrodynamic Simulations of Binary Neutron Star Coalescence and Stellar Collapse with Multipatch Grids</a></td> + <td>Christian Reisswig</td> + <td>California Institute of Technology</td> + <td>&nbsp;</td> + </tr> +</table> + <h3>Past Seminars</h3> <table border="1"> <tr><th>Date</th><th>Title</th><th>Presenter</th><th>Affiliation</th><th>Slides</th><th>Recording</th></tr>