- can be useful either for flow-rate weighting where backflow
  is to be ignored in the average, or for flow-rate weighting
  on surfaces with inconsistent orientation.

  Reworked to code to make better use of Enum (the NamedEnum
  replacement). Enum doesn't require contiguous enumeration values,
  which lets us use bitmasking of similar operations to reduce
  duplicate code.

- this makes it possible to perform additional operations
  on surface values that have been previously sampled.

- support vectorField for weighting operations.

- reduce overhead by avoiding creation of weight fields, Sf fields
  and combined surface geometries unless they are actually required.

- extend some similar concepts and operations to volFieldValue

Patch contributed by Timo Niemi, VTT.
Resolves patch request https://bugs.openfoam.org/view.php?id=2452

- currently only 'none' or 'sqrt', which can be useful in combination
  with integrate or averaging functions.

Renamed the original volRegion -> volFieldValue to clarify the purpose
of this class to process vol fields on a volRegion.

functionObjects::surfaceRegion: Write the surface geometry for formats in which the data is in separate files

Replaced the 'postProcess' argument to the 'write' and 'execute'
functions with the single static member 'postProcess' in the
functionObject base-class.

The use of the term 'source' in the context of post-processing is
confusing and does not properly describe the process of region
selection.  The new names 'surfaceRegion' and 'volRegion' better
describe the purpose of the functionObjects which is to provide field
processing functionality limited to a specified region of space, either
a surface or volume.

The keyword 'source' is renamed 'regionType' which better describes the
purpose which is to specify the method by which the surface or volume
region is selected.

The keyword to select the name of the surface or volume region is
renamed from 'sourceName' to 'name' consistent with the other
name-changes above.

with the more general and flexible 'postProcess' utility and '-postProcess' solver option

Rationale
---------

Both the 'postProcess' utility and '-postProcess' solver option use the
same extensive set of functionObjects available for data-processing
during the run avoiding the substantial code duplication necessary for
the 'foamCalc' and 'postCalc' utilities and simplifying maintenance.
Additionally consistency is guaranteed between solver data processing
and post-processing.

The functionObjects have been substantially re-written and generalized
to simplify development and encourage contribution.

Configuration
-------------

An extensive set of simple functionObject configuration files are
provided in

OpenFOAM-dev/etc/caseDicts/postProcessing

and more will be added in the future.  These can either be copied into
'<case>/system' directory and included into the 'controlDict.functions'
sub-dictionary or included directly from 'etc/caseDicts/postProcessing'
using the '#includeEtc' directive or the new and more convenient
'#includeFunc' directive which searches the
'<etc>/caseDicts/postProcessing' directories for the selected
functionObject, e.g.

functions
{
    #includeFunc Q
    #includeFunc Lambda2
}

'#includeFunc' first searches the '<case>/system' directory in case
there is a local configuration.

Description of #includeFunc
---------------------------

    Specify a functionObject dictionary file to include, expects the
    functionObject name to follow (without quotes).

    Search for functionObject dictionary file in
    user/group/shipped directories.
    The search scheme allows for version-specific and
    version-independent files using the following hierarchy:
    - \b user settings:
      - ~/.OpenFOAM/\<VERSION\>/caseDicts/postProcessing
      - ~/.OpenFOAM/caseDicts/postProcessing
    - \b group (site) settings (when $WM_PROJECT_SITE is set):
      - $WM_PROJECT_SITE/\<VERSION\>/caseDicts/postProcessing
      - $WM_PROJECT_SITE/caseDicts/postProcessing
    - \b group (site) settings (when $WM_PROJECT_SITE is not set):
      - $WM_PROJECT_INST_DIR/site/\<VERSION\>/caseDicts/postProcessing
      - $WM_PROJECT_INST_DIR/site/caseDicts/postProcessing
    - \b other (shipped) settings:
      - $WM_PROJECT_DIR/etc/caseDicts/postProcessing

    An example of the \c \#includeFunc directive:
    \verbatim
        #includeFunc <funcName>
    \endverbatim

postProcess
-----------

The 'postProcess' utility and '-postProcess' solver option provide the
same set of controls to execute functionObjects after the run either by
reading a specified set of fields to process in the case of
'postProcess' or by reading all fields and models required to start the
run in the case of '-postProcess' for each selected time:

postProcess -help

Usage: postProcess [OPTIONS]
options:
  -case <dir>       specify alternate case directory, default is the cwd
  -constant         include the 'constant/' dir in the times list
  -dict <file>      read control dictionary from specified location
  -field <name>     specify the name of the field to be processed, e.g. U
  -fields <list>    specify a list of fields to be processed, e.g. '(U T p)' -
                    regular expressions not currently supported
  -func <name>      specify the name of the functionObject to execute, e.g. Q
  -funcs <list>     specify the names of the functionObjects to execute, e.g.
                    '(Q div(U))'
  -latestTime       select the latest time
  -newTimes         select the new times
  -noFunctionObjects
                    do not execute functionObjects
  -noZero           exclude the '0/' dir from the times list, has precedence
                    over the -withZero option
  -parallel         run in parallel
  -region <name>    specify alternative mesh region
  -roots <(dir1 .. dirN)>
                    slave root directories for distributed running
  -time <ranges>    comma-separated time ranges - eg, ':10,20,40:70,1000:'
  -srcDoc           display source code in browser
  -doc              display application documentation in browser
  -help             print the usage

 pimpleFoam -postProcess -help

Usage: pimpleFoam [OPTIONS]
options:
  -case <dir>       specify alternate case directory, default is the cwd
  -constant         include the 'constant/' dir in the times list
  -dict <file>      read control dictionary from specified location
  -field <name>     specify the name of the field to be processed, e.g. U
  -fields <list>    specify a list of fields to be processed, e.g. '(U T p)' -
                    regular expressions not currently supported
  -func <name>      specify the name of the functionObject to execute, e.g. Q
  -funcs <list>     specify the names of the functionObjects to execute, e.g.
                    '(Q div(U))'
  -latestTime       select the latest time
  -newTimes         select the new times
  -noFunctionObjects
                    do not execute functionObjects
  -noZero           exclude the '0/' dir from the times list, has precedence
                    over the -withZero option
  -parallel         run in parallel
  -postProcess      Execute functionObjects only
  -region <name>    specify alternative mesh region
  -roots <(dir1 .. dirN)>
                    slave root directories for distributed running
  -time <ranges>    comma-separated time ranges - eg, ':10,20,40:70,1000:'
  -srcDoc           display source code in browser
  -doc              display application documentation in browser
  -help             print the usage

The functionObjects to execute may be specified on the command-line
using the '-func' option for a single functionObject or '-funcs' for a
list, e.g.

postProcess -func Q
postProcess -funcs '(div(U) div(phi))'

In the case of 'Q' the default field to process is 'U' which is
specified in and read from the configuration file but this may be
overridden thus:

postProcess -func 'Q(Ua)'

as is done in the example above to calculate the two forms of the divergence of
the velocity field.  Additional fields which the functionObjects may depend on
can be specified using the '-field' or '-fields' options.

The 'postProcess' utility can only be used to execute functionObjects which
process fields present in the time directories.  However, functionObjects which
depend on fields obtained from models, e.g. properties derived from turbulence
models can be executed using the '-postProcess' of the appropriate solver, e.g.

pisoFoam -postProcess -func PecletNo

or

sonicFoam -postProcess -func MachNo

In this case all required fields will have already been read so the '-field' or
'-fields' options are not be needed.

Henry G. Weller
CFD Direct Ltd.

This changes simplifies the specification of functionObjects in
controlDict and is consistent with the 'libs' option in controlDict to
load special solver libraries.

Support for the old 'functionObjectLibs' name is supported for backward compatibility.

  - Avoids the need for the 'OutputFilterFunctionObject' wrapper
  - Time-control for execution and writing is now provided by the
    'timeControlFunctionObject' which instantiates the processing
    'functionObject' and controls its operation.
  - Alternative time-control functionObjects can now be written and
    selected at run-time without the need to compile wrapped version of
    EVERY existing functionObject which would have been required in the
    old structure.
  - The separation of 'execute' and 'write' functions is now formalized in the
    'functionObject' base-class and all derived classes implement the
    two functions.
  - Unnecessary implementations of functions with appropriate defaults
    in the 'functionObject' base-class have been removed reducing
    clutter and simplifying implementation of new functionObjects.
  - The 'coded' 'functionObject' has also been updated, simplified and tested.
  - Further simplification is now possible by creating some general
    intermediate classes derived from 'functionObject'.

Construction failure and recovery is not handled with exceptions in functionObjectList

functionObjects: Moved into the functionObjects namespace and rationalized and simplified failable construction

Rather than requiring each functionObject to handle failed construction
internally (using the active_ flag) the static member function "viable"
is provided which returns true if construction of the functionObject is
likely to be successful.  Failed construction is then handled by the
wrapper-class which constructs the functionObject,
e.g. "OutputFilterFunctionObject".

faceSource: Added weightedAreaAverage option
Resolves bug-report http://www.openfoam.org/mantisbt/view.php?id=1769

Resolves bug-report http://www.openfoam.org/mantisbt/view.php?id=1693

Previous behavior which may be useful for moving-mesh cases can be
selected using the optional entry:
    writeTotalArea  yes;

The initial total area is written in the log and data file header e.g.:

 #   Source : faceZone f0
 #   Faces  : 8
 #   Area   : 1.063860e-02