[CIG-MC] internal vbcs in CitcomS

[tan2]

Dan,

You will need to call construct_id() after step (2) to update the id array
as well.

Eh

On Tue, Jul 23, 2013 at 11:22 AM, Dan Bower <dan at caltech.edu> wrote:

> Hi CIG,
>
> I have a CitcomS developer question relating to internal velocity
> boundary conditions.  Broadly speaking, this is what I am doing (for
> each timestep):
>
> (1) read in internal velocity bcs from file
> (2) update NODE[level][m][nodel] (turning VBs on, SBs off).  This
> requires a bit of work to be consistent with the multigrid solver, but
> I think I have that sorted.
> (3) recall 'get_bcs_id_for_residual' to update zero_resid[level][m][j]
> and E->num_zero_resid[level][m]
>
> This algorithm appears to work well for simple regional cases (simple
> meaning, e.g., applying internal velo bcs to a line of nodes at a
> fixed depth).  For global cases, with a more complicated distribution
> of internal bcs, the solver does not converge (I'm testing with an
> isoviscous model to keep it simple), e.g.:
>
> Momentum equation force 9.832610840e+04
>  *  residual (050) = 5.075e+04 from 9.833e+04 to 4.916e+02 in 71.19 secs
> Warning: solver not converging! 0
> (000)  71.3 s v=1.245233e+04 p=0.000000e+00 div/v=1.72e+01
> dv/v=1.00e+00 dp/p=1.00e+00 step 0
>  *  residual (050) = 1.313e+03 from 4.688e+04 to 4.916e+02 in 71.37 secs
> Warning: solver not converging! 1
> (001) 142.7 s v=7.169507e+03 p=4.552888e+05 div/v=6.55e+00
> dv/v=1.26e+00 dp/p=1.00e+00 step 0
>  *  residual (050) = 1.661e+06 from 2.424e+04 to 4.916e+02 in 71.74 secs
> Warning: solver not converging! 1
>
>
> Therefore, I have a couple of questions:
>
> (1) I am missing something from my algorithm in 1-3 above?
>
> (2) Does anyone have any guiding principles in applying internal
> velocity bcs such that a solver (particularly the multigrid in
> CitcomS) will converge?
>
> Thanks in advance for any suggestions,
>
> Dan
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