[ET Trac] [Einstein Toolkit] #1070: EOS_Omni::poly_gamma_ini should default to poly_gamma

Einstein Toolkit trac-noreply at einsteintoolkit.org
Tue Sep 4 09:47:09 CDT 2012

#1070: EOS_Omni::poly_gamma_ini  should default to poly_gamma
  Reporter:  knarf                  |       Owner:                     
      Type:  enhancement            |      Status:  review             
  Priority:  minor                  |   Milestone:                     
 Component:  EinsteinToolkit thorn  |     Version:  development version
Resolution:                         |    Keywords:                     

Comment (by knarf):

 Right. I also find it a bit confusing to have cgs units used for constants
 in the code but then transforming back and forth all the time to cancel
 them out again. At the moment, a polytrope is calculated as p = K *
 rho^poly_gamma * magic_number^(poly_gamma_ini - poly_gamma) where
 magic_number is defined in EOS_Omni_Module.F90 with the comment:

 > Magic numbers in convenient units, calculated by someone whom we trust
 to have worked very carefully

 I think there are two separate issues here. The first is the question why
 these units are used in the first place - why converting poly_k to
 poly_k_cgs if inside the EOS we use p_gf and rho_gf to reverse it again.

 The second issue is that at the moment poly_gamma_ini isn't really doing
 what it is supposed to be doing. It would be correct if poly_k_cgs would
 be reset to poly_k * rho_gf^poly_gamma / p_gf after it has been used for
 initial data.

Ticket URL: <https://trac.einsteintoolkit.org/ticket/1070#comment:6>
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