Changes between Version 230 and Version 231 of doc/app/errmsg

Timestamp:

Apr 6, 2016 2:52:33 PM (9 years ago)

Author:

raasch

Comment:

--

doc/app/errmsg

@@ -277 +277 @@
 ||[=#PA0235 PA0235]   ||mg_switch_to_pe0_level out of range and reset to default (=0)   ||  ||
 ||[=#PA0236 PA0236]   ||grid coarsening on subdomain level cannot be performed  || The multigrid pressure solver halfs the number of grid points in each direction to get coarser grid levels. This is done for the subdomains on each PE until one of the directions cannot be divided by 2 without rest. If this is the case, the coarsest grid level of each subdomain are gathered on each PE for further coarsening. Before gathering, the coarsening must be done for the subdomain at least one time. You get this error messages for example with the following combination: \\ [../inipar#nx  nx ] = 60, [../inipar#ny  ny ] = 60, [../inipar#nz  nz ] = 60, \\ [../d3par#npex  npex ] = 4, [../d3par#npey  npey ] = 2. \\ With this combination, the subdomain on each PE has the size: \\ nx = 15, ny = 30, nz = 60. \\ The number of grid points in the x-direction of the subdomain cannot be divided by 2 and no coarsening is possible for the subdomains in this example. \\\\ To avoid this error ensure that the number of grid points in each direction can be divided by 2 without rest on the subdomain of an PE at least one time. Therefor vary the number of grid points for the direction which does not fit by changing [../inipar#nx  nx ], [../inipar#ny  ny ] or [../inipar#nz  nz ] or adjust the number of processors by modifying the parameters [../d3par#npex  npex ] or [../d3par#npey  npey ] in order to get other subdomain sizes. \\ In the example given above, you can avoid the error by changing nx or npex. For example setting [../inipar#nx  nx ] = 64 leads to a subdomain of \\ nx = 16, ny = 30, nz = 60. \\ All numbers are now divisible by 2 without rest and the first coarser grid on the subdomain is then: \\ nx = 8, ny = 15, nz = 30. ||
-||[=#PA0237 PA0237]   ||multigrid gather/scatter impossible in non parallel mode   || Siggi ||
+||[=#PA0237 PA0237]   ||multigrid gather/scatter impossible in non parallel mode   ||You are using the multigrid-solver and are running PALM in non-parallel mode (i.e. on a single processor core), but you have set a multigrid level (using parameter [../inipar#mg_switch_to_pe0_level mg_switch_to_pe0_level]) from where on data shall be collected on core 0 in order to allow for a further coarsening of the grid. Obviously, this does not make sense if only one core is used. Remove this parameter from your NAMELIST-file or set it to value ''-1'' to switch of collection. ||
 ||[=#PA0238 PA0238]   ||more than 10 multigrid levels   ||You have selected the multigrid Poisson-solver ([../inipar#psolver psolver] = ''"multigrid"'') and a numerical grid which allows for more than 10 coarsening levels. This may happen for very large grids where the grid point numbers along x,y,z are given by 2^n^ with n>10. The smallest grid which may cause this error would have 2048^3^ points. However, depending on the chosen domain decomposition, much larger grids might be possible. Choose a different number of grid points to circumvent this problem. ||
 ||[=#PA0239 PA0239]   ||The value for "topography_grid_convention" is not set. Its default value is only valid for "topography" = "single_building", "single_street_canyon" or "read_from_file" Choose "cell_edge" or "cell_center".   ||  ||