[Users] problems about binary neutron star simulations

HUI Hon Ka hkhui at phy.cuhk.edu.hk
Wed Jul 22 02:19:13 CDT 2020


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

--
Open WebMail Project (http://openwebmail.org)



More information about the Users mailing list