MHD implementation details and discussions
Contents
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
- See Josh Faber's notes here [1], or check out the code (still a work in progress!!!) here [2].
- Josh Faber will commit the routines mentioned in these notes soon.
- Scott Noble is working Con2PrimM, will hopefully commit by the end of this week (or next week at least).
Subprojects
| Task | Main people | Notes |
|---|---|---|
| Riemann Problem | Scott Noble | |
| Con2Prim | Christian Ott | from Harm3D |
| Constraint transport | Scott Noble | from Harm3D |
| Reconstruction | Frank Löffler | |
| Failure Recovery Procedure | Scott Noble | |
| Carpet Refluxing | Erik Schnetter | Finished? |
| EMF Restriction/Prolongation | ||
| Constraint Damping? |
During the Cactus workshop, some progress was made on implementing MHD within GRHydro by reimplementing various subroutines with alternate versions for MHD and calling them out with the MHD flag in the scheduler. Basically, instead of GRHydro_filename.F90, we will have GRHydro_filenameM.F90.
