From OpenFOAMWiki

It maps fields from a case to another. The syntax is:

   mapFields <source root> <source case> <target root> <target case> [-consistent] [-parallelSource] [-parallelTarget]

The available options are the following:

  • -consistent: it maps a field consistently. The source and the destination have the same geometry. If this option is not specified, it is necessary to define a dictionary named mapFieldsDict in the system directory of the case.
  • -parallelSource: it specifies the source case is decomposed for parallel calculation.
  • -parallelTarget: it specified the destination case is decomposed for parallel calculation.

The syntax of the mapFieldsDict is the following:

   <coincident patches in the two cases>
   <target patches who has to be mapped from the original internal field now cut by patches>

An example of use can be found in the official OpenFOAM user's guide (see page U-31: mapFields ../cavity -consistent)