[Users] problems about binary neutron star simulations

Roland Haas rhaas at illinois.edu
Fri Jul 24 09:43:34 CDT 2020


Hello Hon-ka,

please take a look at this email thread:

http://lists.einsteintoolkit.org/pipermail/users/2018-January/006030.html

where similar issues have been addressed. The group in Parma made their
parameter files available for download.

The URL to the Parma server changed and is now:

https://einstein.pr.infn.it/gravity/Research/BNS2015.html

Yours,
Roland

> Dear all,
> 
> I encountered some problem while carrying out some binary neutron star simulations 
> and would like to know if anyone can help me out.
> 
> I followed the BNS example on the site (nsnstohmns) but adopted the "Hybrid" eos for
> the BNS Meudon initial data generated with certain tabular nuclear models. 
> 
> 
> #####-----#####-----#####-----#####-----#####-----#####-----#####-----#####-----#####
> Problem 1: 
> 
> I understand that I need to assign the following parameters accordingly, 
> Meudon_Bin_NS::eos_table = "Hybrid"
> EOS_Omni::hybrid_gamma_th
> EOS_Omni::n_pieces
> EOS_Omni::hybrid_k0
> EOS_Omni::hybrid_gamma[]
> EOS_Omni::hybrid_rho[]
> 
> but I am not sure whether it is correct to also set
> GRHydro::GRHydro_eos_table = "Hybrid" ?
> or should I set
> GRHydro::GRHydro_eos_table = "Ideal_Fluid" ?
> 
> In the BNS example nsnstohmns, despite using a polytropic BNS model, the parameter file shows
> GRHydro::GRHydro_eos_type  = "General"          instead of  "Polytype"
> GRHydro::GRHydro_eos_table  = "Ideal_Fluid"          instead of "2D_Polytrope"
> What is the particular reason for this setting ??
> 
> 
> #####-----#####-----#####-----#####-----#####-----#####-----#####-----#####-----#####
> Problem 2: 
> 
> Here is one of the error I encountered.
> 
> WARNING level 1 from host emc4 process 0
>   in thorn CarpetLib, file /home/hkhui/Cactus/configs/sim/build/CarpetLib/dh.cc:161:
>   ->   
> /home/hkhui/Cactus/configs/sim/build/CarpetLib/dh.cc:837:
>    [ml=0 rl=7 c=0] The following grid structure consistency check failed:
>    Refinement prolongation: All points must have been received
>    needrecv.empty()
> WARNING level 1 from host emc4 process 0
>   in thorn CarpetLib, file /home/hkhui/Cactus/configs/sim/build/CarpetLib/dh.cc:161:
>   ->   
> /home/hkhui/Cactus/configs/sim/build/CarpetLib/dh.cc:983:
>    [ml=0 rl=7 c=0] The following grid structure consistency check failed:
>    Synchronisation and boundary prolongation: All points must have been received
>    needrecv.empty()
> 
> It seems this error is associated with the following settings in the parfile
> CoordBase::xmin =    0.00
> CoordBase::ymin = -396.00
> CoordBase::zmin =    0.00
> CoordBase::xmax = +396.00
> CoordBase::ymax = +396.00
> CoordBase::zmax = +396.00
> CoordBase::dx   =    9.00
> CoordBase::dy   =    9.00
> CoordBase::dz   =    9.00
> CarpetRegrid2::num_levels_1 = 7
> CarpetRegrid2::position_x_1 = 15.1875
> CarpetRegrid2::radius_1[1]  =240.0
> CarpetRegrid2::radius_1[2]  =120.0
> CarpetRegrid2::radius_1[3]  = 60.0
> CarpetRegrid2::radius_1[4]  = 28.125   # nsnstohmns 26.125
> CarpetRegrid2::radius_1[5]  = 19.875   # nsnstohmns 17.875
> CarpetRegrid2::radius_1[6]  = 11.0   # nsnstohmns 13
> 
> The initial size of the stars of my model:
> Coordinate separation between the two stellar centers : 45 km
> Coordinate equatorial radius (phi=0) a1 =    10.16960419148 km
> Coordinate equatorial radius (phi=pi/2) a2 = 9.872118702179 km
> Coordinate equatorial radius (phi=pi):       10.19931065979 km
> Coordinate polar radius a3 =                 9.925176860927 km
> 
> I used the nsnstohmns parfile while changing the eos part and the resolution only,
> for the set of par above, I set [5] and [6] so that they together cover the separation (19.875+11 M > 45km)
> and I set [4] so that this refinement region of the 1st star cover some region of the 2nd star.
> I would like to know if there is any rule for setting the AMR region (the radius par above),
> I varied these radius parameters and end up with either error about the grid structure (see 
> above err message) or the c2p conversion error, but never been able to carry out simulation to merger.
> If the problem is not about the AMR region radius setting, what could be the problem?
> 
> 
> #####-----#####-----#####-----#####-----#####-----#####-----#####-----#####-----#####
> Problem 3:
> 
> I have carried the BNS simulation with stars of slightly larger R initially with my nuclear eos,
> and adopted exactly the same parfile setting as nsnstohmns with Time::dtfac = 0.35,
> it happens that the NSTracker thorn loses track of the stars.
> The rho_max position suddenly moved so fast that I suspect the result is wrong.
> And the position of the star is not updated anymore after certain time step.
> What could cause such false result??
> 
> -----------------------------------------------------------------------------------------------------------------------
> Iteration      Time | *me_per_hour |             GRHYDRO::dens | *ROBASE::rho | *::w_lorentz | *STRAINTS::H | *axrss_mb
>                     |              |          sum      maximum |      maximum |      maximum |      maximum |   maximum
> -----------------------------------------------------------------------------------------------------------------------
> INFO (NSTracker): Found star at (15.1875,0.28125,0)
>       200     4.922 |  113.9376773 |    0.0001258    0.0027456 |    0.0011040 |    1.3729137 |    0.0031954 |       989
> INFO (NSTracker): Found star at (15.1875,0.5625,0)
>       400     9.844 |  114.5209435 |    0.0001258    0.0026962 |    0.0011407 |    1.5612539 |    0.0050456 |       991
> INFO (NSTracker): Found star at (15.1875,0.84375,0)
>       600    14.766 |  114.7115204 |    0.0001259    0.0014155 |    0.0006785 |    1.6008531 |    0.0038587 |       993
> INFO (NSTracker): Found star at (15.1875,1.125,0)
>       620    15.258 |  114.1468585 |    0.0001259    0.0011319 |    0.0005486 |    1.6009425 |    0.0036545 |      1084
> INFO (NSTracker): Found star at (14.9062,1.6875,0)
>       660    16.242 |  113.7788398 |    0.0001259    0.0007284 |    0.0003032 |    1.6088940 |    0.0033746 |      1084
> INFO (NSTracker): Found star at (14.9062,1.96875,0)
>       668    16.439 |  113.6618707 |    0.0001259    0.0006774 |    0.0002687 |    1.6088572 |    0.0033143 |      1084
> INFO (NSTracker): Found star at (14.625,1.96875,0)
>       672    16.537 |  113.4731182 |    0.0001259    0.0006559 |    0.0002538 |    1.6088969 |    0.0032825 |      1084
> INFO (NSTracker): Found star at (14.625,2.25,0)
>       676    16.636 |  112.2718493 |    0.0001259    0.0006351 |    0.0002415 |    1.6090522 |    0.0032501 |       993
> INFO (NSTracker): Found star at (14.625,2.53125,0)
>       684    16.833 |  112.1253398 |    0.0001259    0.0005958 |    0.0002184 |    1.6093073 |    0.0031844 |       993
> INFO (NSTracker): Found star at (14.625,2.8125,0)
>       688    16.931 |  111.9626309 |    0.0001259    0.0005780 |    0.0002090 |    1.6111194 |    0.0031493 |       993
> 
> ...
> 
> INFO (NSTracker): New star location not set (0.5625,-0.28125,0) because too far from old (13.7812,7.875,0).
>       884    21.755 |   99.6235324 |    0.0001259    0.0002227 |    0.0000792 |    1.9277784 |    0.0066220 |      1183
> INFO (NSTracker): New star location not set (0.84375,0.28125,0) because too far from old (13.7812,7.875,0).
>      1004    24.708 |   99.9757198 |    0.0001259    0.0001761 |    0.0001082 |    2.0183873 |    0.0088739 |      1183
> INFO (NSTracker): New star location not set (1.125,-0.5625,0) because too far from old (13.7812,7.875,0).
>      1008    24.806 |  100.0596083 |    0.0001259    0.0001782 |    0.0001092 |    2.0194414 |    0.0089929 |      1183
> 
> ...
> 
> INFO (NSTracker): New star location not set (3.9375,-21.375,0) because too far from old (13.7812,7.875,0).
>      2244    55.223 |   99.3936843 |    0.0001258    0.0000634 |    0.0000347 |    2.5307425 |    0.0051844 |      1189
> 
> ...
> 
> INFO (NSTracker): New star location not set (11.25,-45,33.75) because too far from old (13.7812,7.875,0).
>      4028    99.127 |   98.5126340 |    0.0001270    0.0000141 |    0.0000075 |    3.0658306 |    0.0034565 |      1190
> 
> #####-----#####-----#####-----#####-----#####-----#####-----#####-----#####-----#####
> 
> 
> Any help will be greatly appreciated.. 
> 
> Yours,
> Hon-ka
> 
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