= Nesting =
A multi-scale nesting system is available since rXXXX. It currently undergoes major testing and revisions. A detailed description will follow after the official release.

== Job preparation ==
The following example provide a step-by-step tutorial on how to set up a nesting system with one parent (root) domain and two child domains.

1. Prepare parameter files for all domains, e.g. for run with topography and separate topography data for each domain:
{{{
testrun_p3d (root/parent domain)
testrun_01_p3d (child domain 1)
testrun_02_p3d (child domain 2)
testrun_topo
testrun_01_topo
testrun_02_topo
}}}

2. The nesting system is activated by specifying a {{{&nestpar}}} NAMELIST in the _p3d file of the '''root domain''', e.g.:
{{{
 &nestpar domain_layouts = 'root domain',      1,  -1,  24,    0.0,    0.0,
                           'child domain 1',   2,   1,  24,  100.0,  100.0,
                           'child domain 2',   3,   1,  24,  200.0,  200.0,
          nesting_datatransfer_mode = 'mixed',
          nesting_mode = 'two-way',
/
}}}
For details on the parameters, see [wiki:doc/app/nestpar#nestpar nestpar].

3. Add file connection statements for all child domains to the {{{.mrun.config}}} file, 
{{{
#----------------------------------------------------------------------------
# List of input-files for nested model runs
#----------------------------------------------------------------------------
PARIN_01                  in:job        nest#      $base_data/$fname/INPUT   _01_p3d
PARIN_02                  in:job        nest#      $base_data/$fname/INPUT   _02_p3d
TOPOGRAPHY_DATA_01        in:locopt     nest#      $base_data/$fname/INPUT   _01_topo
TOPOGRAPHY_DATA_02        in:locopt     nest#      $base_data/$fname/INPUT   _02_topo
}}}

4. Execute {{{mrun}}} and specify the nesting input files, i.e.,
{{{
mrun -d testrun -r "d3# nest# ts# pr# ..." -X "72" ...
}}}
Make sure that the total number of PEs (here 72) the sum of the PEs allocated for the individual domains (3 x 24).