Hooks - run custom code at given times during a simulation¶

Hooks allows you to run code at given times during a simulation

• pre_simulation

• post_simulation

• pre_timestep

• post_timestep

Each hook is described be the following

name

The name of the hook, used for better log and error messages

enabled

Flag to turn the hook on or off. Default on

code

The Python code to run. You can access the simulation object which gives access to all fields and every part of the simulation that the normal Ocallaris code can access. You also have all user code constants instantly available just like all other code in the input file.

The example below shows that each hook gets it’s own dictionary hook_data to store whatever it wants between calls. The example also shows how to read the input file parameters in a hook that is defined in the same input file, and how to perform output to file in a configurable manner:

hooks:
    post_timestep:
    -   name: save colour function field
        enabled: yes
        code: |
            if not 'cf' in hook_data:
                prefix = simulation.input.get_value('output/prefix')
                hook_data['cf'] = File(prefix + '_c.pvd')
            if t > 1:
                hook_data['cf'] << (c, t)

The hook_data dictionary is saved to restart files and the contents are brought back as long as it consists of basic data types (lists, dicts, strings, numbers) since the data is internally serialized to ASCII YAML format before saving to HDF5 (which is the binary format of the restart file).