[petsc-users] Parallelize in the y direction

[Joauma Marichal]

 Dear Sir or Madam,

I am looking for advice regarding some of PETSc functionnalities. I am currently using PETSc to solve the Navier-Stokes equations on a 3D mesh decomposed over several processors.  However, until now, the processors are distributed along the x and z directions but not along the y one. Indeed, at some point in the algorithm, I must solve a tridiagonal system that depends only on y. Until now, I have therefore performed something like this:
for(int k = cornp->zs, k<cornp->zs+cornp->zm; ++k){
     for(int i = cornp->xs, i<cornp->xs+cornp->xm; ++i){
           Create and solve a tridiagonal system for all the y coordinates (which are on the same process)
}
However, I would like to decompose my mesh in the y direction (as this should improve the code efficiency).
I managed to do so by creating a system based on the 3D DM of all my case (so 1 system of size x*y*z). Unfortunately, this does not seem to be very efficient.
Do you have some advice on how to cut in the y direction while still being able to solve x*z systems of size y? Should I create 1D DMs?

Thanks a lot for your help.

Best regards,

Joauma Marichal
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