Difference between revisions of "MHD implementation details and discussions"

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(Summarizing some code decisions reached at the Carpet workshop)
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</ul>
 
</ul>
  
<h2>Conventions / Variable names ect.</h2>
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<h2>Conventions / Variable names etc.</h2>
 
<ul>
 
<ul>
 
  <li> Principally follow the Valencia formulation as out-lined in [http://adsabs.harvard.edu/abs/2006ApJ...637..296A Anton et al. (2006)] </li>  
 
  <li> Principally follow the Valencia formulation as out-lined in [http://adsabs.harvard.edu/abs/2006ApJ...637..296A Anton et al. (2006)] </li>  
 
  <li> HydroBase's Bvec[1-3] GF will be identified with Valencia's  B^i  vector  </li>
 
  <li> HydroBase's Bvec[1-3] GF will be identified with Valencia's  B^i  vector  </li>
 
  <li> Bvec[] will be used both as an evolved quantity and a primitive variable</li>
 
  <li> Bvec[] will be used both as an evolved quantity and a primitive variable</li>
  <li> Introduce "densitized_state" as a scalar that controls interpretation of Bvec[]'s meaning; </li>
+
  <li> During the Carpet workshop, we concluded it is easier to define B^i to be the undensitized magnetic field; this requires some care, since psi^6 B^i is the quantity that appears in the evolution equation, but simplifies the rest of the code
<li> if( densitized_state) then  Bvec[] = B^i \sqrt(\gamma)    else  Bvec[] = B^i </li>
 
 
  <li> Only use locally calculated "comoving magnetic tensor" b^a when needed </li>
 
  <li> Only use locally calculated "comoving magnetic tensor" b^a when needed </li>
 +
<li> In general, but especially for MHD, it seems worthwhile to promote sqrt(gamma)=psi^6 to an independent gridfunction
 
</ul>
 
</ul>
 
  
 
<h2>Subprojects</h2>
 
<h2>Subprojects</h2>

Revision as of 03:46, 29 August 2010

Scientific Goals

Random bits and pieces

  • Reuse parts of Harm3D

Conventions / Variable names etc.

  • Principally follow the Valencia formulation as out-lined in Anton et al. (2006)
  • HydroBase's Bvec[1-3] GF will be identified with Valencia's B^i vector
  • Bvec[] will be used both as an evolved quantity and a primitive variable
  • During the Carpet workshop, we concluded it is easier to define B^i to be the undensitized magnetic field; this requires some care, since psi^6 B^i is the quantity that appears in the evolution equation, but simplifies the rest of the code
  • Only use locally calculated "comoving magnetic tensor" b^a when needed
  • In general, but especially for MHD, it seems worthwhile to promote sqrt(gamma)=psi^6 to an independent gridfunction

Subprojects

Task Main people Notes
Riemann Problem Scott Noble
Con2Prim Christian Ottfrom Harm3D
Constraint transport Scott Noble from Harm3D
Reconstruction Frank Löffler
Failure Recovery Procedure Scott Noble
Carpet Refluxing
EMF Restriction/Prolongation