4.3 User-defined parameters

Parameter name

Type

Default 
value

Explanation
data_output_pr_userC * 10
(200)		200 * ' 'User defined quantities for which horizontally averaged profile data is to be output.

Beside the PALM standard output quantities (which can be selected via parameter data_output_pr), the user can define (without any restriction) additional output quantities (e.g. turbulent resolved-scale horizontal momentum fluxes, etc.). Each of these quantities has to be given a unique identifier (string) which must be different from the strings defining the standard output quantities (see list from the description of data_output_pr). Data output can be switched on by assigning the respective strings to data_output_user.

The user has to calculate/provide the respective data array(s) by appropriately extending the user interface (see 3.5.4).

For further steering of the user defined output (output times, cross section levels, time averaging, etc.), the steering parameters for data_output_pr apply accordingly.
data_output_userC * 10 (100)100 * ' 'User defined quantities for which 2d cross section and/or 3d volume data are to be output.

Beside the PALM standard output quantities (which can be selected via parameter data_output), the user can define (without any restriction) additional output quantities (e.g. the temperature variance, etc.). Each of these quantities has to be given a unique identifier (string) which must be different from the strings defining the standard output quantities (see list from the description of data_output). Data output can be switched on by assigning the respective strings to data_output_user.

The user has to calculate/provide the respective data array(s) by appropriately extending the user interface (see 3.5.4).

For further steering of the user defined output (output times, cross section levels, time averaging, etc.), the steering parameters for data_output apply accordingly.

Example:
If the user defined output quantity is the temperature variance and if the user has chosen the string 'pt2' as an identifier for this quantity, then output of horizontal cross sections can be selected by assigning data_output_user = 'pt2_xy'.

region

C*40 (0:9)

 

Name(s) of the subdomain(s) defined by the user. 

With this variable, names can be assigned to the subsections defined by the user (see statistic_regions) which afterwards appear in the headers of the respective files (PLOT1D_DATA) and within the respective plots. Up to 9 subdomains are allowed (region (1) to region (9)), the total domain has the index 0 (region (0)).
topography_grid_
convention		C*11default depends on value of topography; see text for detailsConvention for defining the topography grid.

Possible values are
  • 'cell_edge': the distance between cell edges defines the extent of topography. This setting is normally for generic topographies, i.e. topographies that are constructed using length parameters. For example, topography = 'single_building' is constructed using building_length_x and building_length_y. The advantage of this setting is that the actual size of generic topography is independent of the grid size, provided that the length parameters are an integer multiple of the grid lengths dx and dy. This is convenient for resolution parameter studies.
  • 'cell_center': the number of topography cells define the extent of topography. This setting is normally for rastered real topographies derived from digital elevation models. For example, topography = 'read_from_file' is constructed using the input file TOPOGRAPHY_DATA. The advantage of this setting is that the rastered topography cells of the input file are directly mapped to topography grid boxes in PALM.
The example files example_topo_file and example_building in trunk/EXAMPLES/ illustrate the difference between both approaches. Both examples simulate a single building and yield the same results. The former uses a rastered topography input file with 'cell_center' convention, the latter applies a generic topography with 'cell_edge' convention.

The default value is
  • 'cell_edge' if topography = 'single_building' or 'single_street_canyon',
  • 'cell_center' if topography = 'read_from_file',
  • none (' ' ) otherwise, leading to an abort if topography_grid_convention is not set.
This means that
  • For PALM simulations using a user-defined topography, the topography_grid_convention must be explicitly set to either 'cell_edge' or 'cell_center'.
  • For PALM simulations using a standard topography ('single_building', 'single_street_canyon' or 'read_from_file'), it is possible but not required to set the  topography_grid_convention because appropriate default values apply.

 
 


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