Dear all,
I am trying to perform a magnetised TOV simulation using Einstein Toolkit and Spritz GRMHD code. In particular, currently I have a subroutine that adds a dipolar magnetic field to the TOV star after its initial data has been generated via TOVSolver thorn. Within this subroutine, I have added the following lines that print the 'cctk_time' value as:
character(len=200) warnline WRITE( warnline, '( "cctk_time: ", g16.7)' ) cctk_time call CCTK_INFO(warnline)
This subroutine is scheduled in HydroBase_Con2Prim after Con2Prim step. And I get the following lines in the .out file as: .........
INFO (TOVSolver): Integrated TOV equation
INFO (TOVSolver): Information about the TOVs used:
INFO (): TOV radius mass bary_mass mass(g) cent.rho rho(cgi) K K(cgi) Gamma
INFO (): 1 8.12502 1.40016 1.50618 2.78e+33 0.00128 7.92e+14 100 1.45e+05 2
INFO (TOVSolver): Not using old matter initial data
INFO (TOVSolver): Done interpolation.
INFO (Spritz_DipoleAndAtmo): cctk_time: 0.000000
INFO (Spritz_DipoleAndAtmo): Adding a poloidal magnetic field to the TOV star on reflevel 0
INFO (Spritz_DipoleAndAtmo): Adding atmo to the TOV star on reflevel = '0'
INFO (Spritz_DipoleAndAtmo): cctk_time: 0.000000
-----------------------------------------------------------------------------------------------------------------------------------
Iteration Time | ADMBASE::alp | HYDROBASE::rho | HYDROBASE::press | SPRITZ::B_norm
| minimum maximum | minimum maximum | minimum maximum | minimum maximum
-----------------------------------------------------------------------------------------------------------------------------------
0 0.000 | 0.6698612 0.9603815 | 5.827798e-11 0.0012800 | 0.0000000 0.0001638 | 8.399814e-09 0.0000399
INFO (Spritz_DipoleAndAtmo): cctk_time: 0.3906250E-01
INFO (Spritz_DipoleAndAtmo): cctk_time: 0.3906250E-01
INFO (Spritz_DipoleAndAtmo): cctk_time: 0.7812500E-01
INFO (Spritz_DipoleAndAtmo): cctk_time: 0.7812500E-01
1 0.078 | 0.6698612 0.9603833 | 5.827814e-11 0.0012799 | 0.0000000 0.0001638 | 8.294987e-09 0.0000395
INFO (Spritz_DipoleAndAtmo): cctk_time: 0.1171875
INFO (Spritz_DipoleAndAtmo): cctk_time: 0.1171875
INFO (Spritz_DipoleAndAtmo): cctk_time: 0.1562500
INFO (Spritz_DipoleAndAtmo): cctk_time: 0.1562500
2 0.156 | 0.6698612 0.9603850 | 5.827829e-11 0.0012797 | 0.0000000 0.0001638 | 8.294994e-09 0.0000390
..........
The simulation is performed in uniform grid with dx=dy=dz=0.3125, time::dtfac = 0.25 and HydroBase::timelevels = 2. As you may see from the output lines, in between iteration 0 which is at cctk_time=0.0 and iteration 1 which is at cctk_time=0.078125, there is an intermediate time step with 'cctk_time=0.0390625' when the subroutine is called.
I was hoping to understand better why this intermediate time step exists between two consecutive iterations, and if there is any documentation I could look at. Any help would be much appreciated.
Thank you very much. Sincerely, Jay Kalinani