Piecewise-Polytrope Equation of State Support in IllinoisGRMHD

Leonardo (Leo) Werneck (a student currently working in my research group) recently documented much of IllinoisGRMHD in Jupyter notebooks and worked with me to add piecewise-polytrope equation of state support to IllinoisGRMHD. The code is open-source and available here:

https://github.com/zachetienne/nrpytutorial/tree/master/IllinoisGRMHD/doc

In addition, the Jupyter notebooks may be browsed via nbviewer:

https://nbviewer.jupyter.org/github/zachetienne/nrpytutorial/tree/master/IllinoisGRMHD/doc/

The updated code agrees to roundoff error with the original IllinoisGRMHD when a single polytrope is chosen, and the central density vs time when evolving piecewise-polytrope TOV stars (we tried the APR4 piecewise-polytrope as described in Read et al.) converges to zero density drift a bit above 2nd order with increased resolution, just like in the single-polytrope case. Further, we have successfully evolved SLy piecewise polytrope BNS initial data through a couple orbits (so far).

One can generate the new piecewise-polytrope enabled IllinoisGRMHD thorn family by cloning the above github repo and running the generate_illinoisgrmhd_from_ipynb_files.sh script in that directory. The IllinoisGRMHD/test directory contains some example parameter files.

Piecewise-Polytrope TOV Solver?

To perform the above piecewise-polytrope TOV tests, we needed a simple TOV solver with this capability (TOVSolver only supp

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2300/update-add-piecewise-polytrope-eos-support