ply_sampled_tracking_module Module

Tracking offers the possibility to extract data from a simulation for given subsections of the mesh and specific points in time.

When the data is given in form of polynomials, it usually is required to perform some kind of sampling to obtain a visualization. The ply_sampled_tracking implements this functionality. See ply_sampling_module for details on the configuration of the sampling strategy and tem_tracking_module for details on the general configuration of trackings (description of mesh subsections to extract data for).

An important special case is the tracking of a single point. In this case no sampling has to be done, instead the polynomial representing the state in the element that contains the requested point needs to be evaluated at this point. This can be configured by setting use_get_point=true in the output subtable of the tracking object.

A complete example looks like this:

tracking = {
  label = 'track_shearhat2D',
  folder = './',
  variable = {'momentum','density','energy'},
  shape = {
    kind = 'canoND',
    object= {
      origin ={0.01*dx, 0., 0.}
    }
  },
  time_control = {
    min = 0,
    max = sim_control.time_control.max,
    interval = {iter = 10}
  },
  output = {
    format = 'ascii',
    use_get_point = true
  }
}

This tracks the state variables (momentum, density and energy) in a single point (0.01*dx, 0, 0) and writes them every ten iteration to an ASCII file. Each point in time gets written on a new line in the same file. If you do not use the use_get_point option (its false by default), and no sampling is active, all degrees of freedom of the field in the element, that contains the point, will be written. You can limit the number of degrees of freedom by setting ndofs to some value. The first mode of the Legendre series is the integral mean, so this is usually the value you want to get. Thus, setting ndofs=1 gives you the averaged value of the element the point is found in. The according output table would then look as follows:

  output = {
    format = 'ascii',
    ndofs = 1
  }

Of course, more complex shapes may be tracked, in that case it usually is not sensible to use ascii output anymore. Instead you are than likely to want to view data later on and accordingly write it in VTK format. For this, a sampling table (see ply_sampling_module) should be considered.