operational models: model parameters

[gjaeger]

JuPedSim - JPScore

• Version : 0.8.4
• Commit hash : v0.8.4-991-g9749a79
• Branch : master

Describe the bug

With this setting

  <model operational_model_id="1" description="gcfm">
    <model_parameters>
      <solver>euler</solver>
      <stepsize>0.01</stepsize>
      <exit_crossing_strategy>3</exit_crossing_strategy>
      <linkedcells enabled="true" cell_size="2.2"/>
      <force_ped  nu="0.1"
                  dist_max="2"
                  disteff_max="3"
                  interpolation_width="0.1"/>
      <force_wall nu="0.2"
                  dist_max="3"
                  disteff_max="2"
                  interpolation_width="0.1"/>
    </model_parameters>

I get the following error message:

[...] [error] The linked-cell size [2.2] should be larger than the force range [3.0]
[...] [error] Could not start simulation. Check the log for prior errors

In my opinion, this problem occurs because the value for the parameter disteff_max is larger than the cell_size for the parameter linkedcells.

Expected behavior In my opinion, a model-specific parameter should override a general parameter. If disteff_max is larger than the cell_size, then the value of disteff_max should be used for the cell_size.

[chraibi]

The idea here is that for long-ranged forces, more neighbors need to be considered.

This restriction is to ensure, that when using LC-neighbors, no other agents are left, although they may be influential.

I prefer not to implicitly override these parameters.

[gjaeger]

The idea here is that for long-ranged forces, more neighbors need to be considered.

Which parameter do you mean by long-ranged forces? Do you mean nu (strength of the force), dist_max (maximum force at contact) or disteff_max (cut-off-radius)?

I prefer not to implicitly override these parameters.

How can we extend the manual? Any suggestions?

[gjaeger]

After a talk with @chraibi, when applying the parameters disteff_max and cell_size, it is important to note that they are related. disteff_max may not be greater than cell_size, otherwise cell_size must be adjusted by the user.

This is illustrated in the following sketch by @chraibi