Nesting

A multi-scale nesting system is available since r1763. 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. topography files or static drivers and separate each file for each domain:

   testrun_p3d (root/parent domain)
   testrun_p3d_N02 (child domain 1)
   testrun_p3d_N03 (child domain 2)
   testrun_topo
   testrun_topo_N02
   testrun_topo_N03
   testrun_static
   testrun_static_N02
   testrun_static_N03
   

Note that numbering of the child domains must start with "02" as "01" is internally reserved for the root domain.

2. The nesting system is activated by specifying a &nesting_parameters NAMELIST in the _p3d file of the root domain, e.g.:

    &nesting_parameters 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,   2,  24,  200.0,  200.0,
             nesting_datatransfer_mode = 'mixed',
             nesting_mode = 'two-way',
   /
   

For details on the parameters, see nestpar.

3. Add file connection statements for all child domains to the .palm.config.xxx file,

   #----------------------------------------------------------------------------
   # List of input-files for nested model runs
   #----------------------------------------------------------------------------
   PARIN_02                  in:job        nest#      $base_data/$fname/INPUT   _02_p3d
   PARIN_03                  in:job        nest#      $base_data/$fname/INPUT   _03_p3d
   TOPOGRAPHY_DATA_02        in:locopt     nest#      $base_data/$fname/INPUT   _02_topo
   TOPOGRAPHY_DATA_03        in:locopt     nest#      $base_data/$fname/INPUT   _03_topo
   #----------------------------------------------------------------------------
   4. Execute {{{palmrun}}} and specify the nesting input files, i.e., 
   {{{
   palmrun -d testrun -r "d3# *" ...
   }}} 
   Make sure that the total number of PEs (here 72) the sum of the PEs allocated for the individual domains (3 x 24).