**process hot_spot

Description

This post processor is used to find locations which are local maxima or mimima of a given variable, and within a specified range, but isolated from other peaks by a given radius. This post computation should be useful for automating fatigue or critical stress analysis when meshes and loading conditions are often changing (see for example the usage with cycle_projection on page ).

Syntax

**process hot_spot \(~\,\) *format fmt-string \(~\,\) *function \(~\,\) *max_val max \(~\,\) *min_val min \(~\,\) *minimum \(~\,\) *num fname \(~\,\) *radius rad \(~\,\) *screen_output \(~\,\) *variable name \(~\,\) *write_nodes fname

The following summarizes the different commands and their parameters:

*format

is used to format the screen output for aesthetic value to the user. The command reads the characters remaining on the same line and uses that as a printf style formatting.

*function

applies a to the selected field values before evaluating the hot spot condition (remember the semicolon after the function declaration).

*max_val

specifies a real value for the maximum values to be considered. This can be used to truncate the analysis to regions of reasonable scale.

*min_val

specifies a real value for the minimum values to be considered. An example use is when regions of a structure do not have a fatigue life prediction (and therefore values of zero), but we are interested in the minimum locations with values over 10 for example.

*minimum

is a switch to indicate that we want minimum values as the hot spot. The default is to search for maximum absolute values.

*num

specifies an integer for the number of values to report.

*radius

specifies a real value for the spatial radius separating the hot spot locations.

*variable

specifies the scalar variable of interest. This can of course be a derived variable coming from previous post processing operations.

*write_nodes

is used to give a file name where a Zmesh compatible node set will be listed in order of the num hot spot points.

Note

This command currently applies to nodal data only.

Example

The following example is from the test case hot_spot.inp in test/Post_test/INP.

***global_post_processing
 **process hot_spot
  *radius   5.
  *variable X
  *num      2
  *function -1.0*x;
  *screen_output

Because we asked for *screen_output the following summary is printed to the standard out (and .msgp file). At the first timestep (t=0) the field is uniform so the first 2 nodes respecting the zone rule are printed. In the following the field is just scaled so the location results are the same. That would of course not be the case in a general FEA analysis.

+++++ HOTSPOT ANALYSIS X +++++
Time:0.000000
  1             -2.00e-01
  7             -2.00e-01
running :  25 %

+++++ HOTSPOT ANALYSIS X +++++
Time:1.000000
  152           -2.80e+00
  309           -2.15e+00
running :  50 %

+++++ HOTSPOT ANALYSIS X +++++
Time:2.000000
  152           -2.10e+00
  309           -1.61e+00
running :  75 %

+++++ HOTSPOT ANALYSIS X +++++
Time:3.000000
  152           -1.40e+00
  309           -1.08e+00