CCTK Hydro
Malcolm Tobias
Washington University
[email protected]
Cactus Workshop - NCSA
Sep 27 - Oct 1 1999
CCTK Hydro: A Status Report
Contributors:
Miguel Alcubierre
Gabrielle Allen
Bernd Bruegmann
Teepanis Chachiyo
Thomas Dramlitsch
Ed Evans
Toni Font
Tom Goodale
Philip Gressman
Paul Lamping
Joan Masso
Mark Miller
Philippos Papadopoulos
Ed Seidel
Nikolaos Stergioulas
Wai-Mo Suen
Malcolm Tobias
Rob Young
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Overview

Cactus 3
 Computational Modules (thorns)
– Initial data
– MAHC hydro
– Newtonian hydro
– Boson stars
– EOS tables
– Analysis tools


Tests

Physics
Cactus 4 conversion
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Initial data

Single NS (TOV)

Rotating NS

Head-on colliding NS

Quasi-equil. Data (Meudon Data)

PN initial data

Test Data (FRW, shockwave)

IVP solver

Coupled Ham. & mom. Constraints!!!

No assumptions of conformal flatness!!!
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MAHC hydro

HRSC methods


coupled to various evolution systems


Roe, Marquina, fluxsplit, ENO, HLLE
ADM, Conformal systems, Bona-Masso
well tested (gr-qc/9811015)
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Newtonian Hydro

HRSC methods
 primarily Roe solver

tested on multiple systems
 single NS


head-on NSs

orbiting NSs
multiple test indicators
 angular momentum

mass

energy
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Boson stars


Coupled to a variety of GR evolution systems
stable over a long time scale
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EOS tables


1D tables

tested for polytropic EOS

other EOS are in, but not yet tested

thermo. consistent interp.
2D tables

still under development

still need incorporated into evolution eqs.
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Analysis tools

Apparent horizon finders

waveform extraction

Newman-Penrose quantities

constraint evaluators
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Tests

gr-qc/9811015


still fighting referee
variety of initial data

shocktube

FRW

single static NS

boosted NS
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Tests: GR-hydro coupling

3 hydro methods tested: Roe, fluxsplit and Marquina

3 GR evolution systems: ADM, BM-Einstein and BM Ricci

often different finite-difference schemes (leapfrog, icn, etc.)

TEST EVERY COMBINATION OF EACH!!!
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Tests: GR-hydro coupling
(2nd order time & space)
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Tests: boosted NS
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Tests: boosted NS
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Tests: boosted NS
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Physics

Phys. Rev. D 58 103002 (1998), gr-qc/9904041, grqc/9909059, Shapiro conjecture head-on collision of NS

evolution of quasi-equilibrium NS data (just beginning)

more on the way ;-)

How to do physics with cactus
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Physics: head-on collision


Shapiro conjecture: can thermal pressure (from shock
heating) delay the collapse in the head-on collision of NS s?
Conjecture holds regardless of mass.
Take 2 1.4 solar mass NS (polytropic EOS, G=2, K=1.16x105
cm5/g/s2), give them a velocity corresponding to Newtonian
infall from infinity, solve the IVP and see what happens!
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Physics: head-on collision
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Physics: head-on collision
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Physics: head-on collision
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Physics: Meudon data
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Physics: How to use Cactus

Cactus is not a black box
 many untested combinations of parameters

top down approach
 check all equations/routines


test for consistency of all terms

test for convergence
bottom up approach
 make sure results look "reasonable"

make sure results are "right"

test for convergence
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Cactus 4.0

Most hydro thorns still under conversion

What we will gain:

AMR infrastructure

better interfacing between GR-hydro solvers

more users=more developers & debuggers
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