fieldAverage: Added periodicRestart option and rationalized naming of restart options

When restarting form a previous calculation, the averaging is continuous or
    may be restarted using the \c restartOnRestart option.

    The averaging process may be restarted after each calculation output time
    using the \c restartOnOutput option or restarted periodically using the \c
    periodicRestart option and setting \c restartPeriod to the required
    averaging period.

    Example of function object specification:
    \verbatim
    fieldAverage1
    {
        type fieldAverage;
        functionObjectLibs ("libfieldFunctionObjects.so");
        ...
        restartOnRestart  false;
        restartOnOutput   false;
        periodicRestart false;
        restartPeriod   0.002;
        fields
        (
            U
            {
                mean            on;
                prime2Mean      on;
                base            time;
                window          10.0;
                windowName      w1;
            }
            p
            {
                mean            on;
                prime2Mean      on;
                base            time;
            }
        );
    }
    \endverbatim

    \heading Function object usage
    \table
        Property        | Description           | Required    | Default value
        type            | type name: fieldAverage | yes |
        restartOnRestart  | Restart the averaging on restart | no | no
        restartOnOutput   | Restart the averaging on output | no | no
        periodicRestart | Periodically restart the averaging | no | no
        restartPeriod   | Periodic restart period | conditional |
        fields          | list of fields and averaging options | yes |
    \endtable

src/postProcessing/functionObjects/field/fieldAverage/fieldAverage/fieldAverage.C

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2011-2015 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2016 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -104,6 +104,21 @@ void Foam::fieldAverage::initialize()
 }
 
 
+void Foam::fieldAverage::restart()
+{
+    Info<< "    Restarting averaging at time " << obr_.time().timeName()
+        << nl << endl;
+
+    totalIter_.clear();
+    totalIter_.setSize(faItems_.size(), 1);
+
+    totalTime_.clear();
+    totalTime_.setSize(faItems_.size(), obr_.time().deltaTValue());
+
+    initialize();
+}
+
+
 void Foam::fieldAverage::calcAverages()
 {
     if (!initialised_)
@@ -111,8 +126,8 @@ void Foam::fieldAverage::calcAverages()
         initialize();
     }
 
-    const label currentTimeIndex =
+    const label currentTimeIndex = obr_.time().timeIndex();
-        static_cast<const fvMesh&>(obr_).time().timeIndex();
+    const scalar currentTime = obr_.time().value();
 
     if (prevTimeIndex_ == currentTimeIndex)
     {
@@ -123,6 +138,12 @@ void Foam::fieldAverage::calcAverages()
         prevTimeIndex_ = currentTimeIndex;
     }
 
+    if (periodicRestart_ && currentTime > restartPeriod_*periodIndex_)
+    {
+        restart();
+        periodIndex_++;
+    }
+
     Info<< type() << " " << name_ << " output:" << nl;
 
     Info<< "    Calculating averages" << nl;
@@ -195,7 +216,7 @@ void Foam::fieldAverage::readAveragingProperties()
     totalTime_.clear();
     totalTime_.setSize(faItems_.size(), obr_.time().deltaTValue());
 
-    if (resetOnRestart_ || resetOnOutput_)
+    if (restartOnRestart_ || restartOnOutput_)
     {
         Info<< "    Starting averaging at time " << obr_.time().timeName()
             << nl;
@@ -255,12 +276,15 @@ Foam::fieldAverage::fieldAverage
     obr_(obr),
     active_(true),
     prevTimeIndex_(-1),
-    resetOnRestart_(false),
+    restartOnRestart_(false),
-    resetOnOutput_(false),
+    restartOnOutput_(false),
+    periodicRestart_(false),
+    restartPeriod_(GREAT),
     initialised_(false),
     faItems_(),
     totalIter_(),
-    totalTime_()
+    totalTime_(),
+    periodIndex_(1)
 {
     // Only active if a fvMesh is available
     if (isA<fvMesh>(obr_))
@@ -293,10 +317,16 @@ void Foam::fieldAverage::read(const dictionary& dict)
 
         Info<< type() << " " << name_ << ":" << nl;
 
-        dict.readIfPresent("resetOnRestart", resetOnRestart_);
+        dict.readIfPresent("restartOnRestart", restartOnRestart_);
-        dict.readIfPresent("resetOnOutput", resetOnOutput_);
+        dict.readIfPresent("restartOnOutput", restartOnOutput_);
+        dict.readIfPresent("periodicRestart", periodicRestart_);
         dict.lookup("fields") >> faItems_;
 
+        if (periodicRestart_)
+        {
+            dict.lookup("restartPeriod") >> restartPeriod_;
+        }
+
         readAveragingProperties();
 
         Info<< endl;
@@ -335,18 +365,9 @@ void Foam::fieldAverage::write()
         writeAverages();
         writeAveragingProperties();
 
-        if (resetOnOutput_)
+        if (restartOnOutput_)
         {
-            Info<< "    Restarting averaging at time " << obr_.time().timeName()
+            restart();
-                << nl << endl;
-
-            totalIter_.clear();
-            totalIter_.setSize(faItems_.size(), 1);
-
-            totalTime_.clear();
-            totalTime_.setSize(faItems_.size(), obr_.time().deltaTValue());
-
-            initialize();
         }
 
         Info<< endl;

src/postProcessing/functionObjects/field/fieldAverage/fieldAverage/fieldAverage.H

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2011-2013 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2016 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -54,12 +54,13 @@ Description
     time are written on a per-field basis to the
     \c fieldAveragingProperties dictionary, located in \<time\>/uniform
 
-    When restarting form a previous calculation, the averaging is continuous.
+    When restarting form a previous calculation, the averaging is continuous or
-    However, the averaging process can be restarted using the \c resetOnRestart
+    may be restarted using the \c restartOnRestart option.
-    option.
 
-    To restart the averaging process after each calculation output time, use
+    The averaging process may be restarted after each calculation output time
-    the \c resetOnOutput option.
+    using the \c restartOnOutput option or restarted periodically using the \c
+    periodicRestart option and setting \c restartPeriod to the required
+    averaging period.
 
     Example of function object specification:
     \verbatim
@@ -68,8 +69,10 @@ Description
         type fieldAverage;
         functionObjectLibs ("libfieldFunctionObjects.so");
         ...
-        resetOnRestart true;
+        restartOnRestart  true;
-        resetOnOutput false;
+        restartOnOutput   false;
+        periodicRestart false;
+        restartPeriod   0.002;
         fields
         (
             U
@@ -94,8 +97,10 @@ Description
     \table
         Property        | Description           | Required    | Default value
         type            | type name: fieldAverage | yes |
-        resetOnRestart | flag to reset the averaging on restart | yes  |
+        restartOnRestart  | Restart the averaging on restart | no | no
-        resetOnOutput| flag to reset the averaging on output | yes |
+        restartOnOutput   | Restart the averaging on output | no | no
+        periodicRestart | Periodically restart the averaging | no | no
+        restartPeriod   | Periodic restart period | conditional |
         fields          | list of fields and averaging options | yes |
     \endtable
 
@@ -156,11 +161,17 @@ protected:
         //- Time at last call, prevents repeated averaging
         label prevTimeIndex_;
 
-        //- Reset the averaging process on restart flag
+        //- Restart the averaging process on restart
-        Switch resetOnRestart_;
+        Switch restartOnRestart_;
 
-        //- Reset the averaging process on output flag
+        //- Restart the averaging process on output
-        Switch resetOnOutput_;
+        Switch restartOnOutput_;
+
+        //- Periodically restart the averaging process
+        Switch periodicRestart_;
+
+        //- Restart period
+        scalar restartPeriod_;
 
         //- Initialised flag
         bool initialised_;
@@ -177,6 +188,9 @@ protected:
             //- Total time counter
             List<scalar> totalTime_;
 
+            //- Index for periodic restart
+            label periodIndex_;
+
 
     // Private Member Functions
 
@@ -190,6 +204,9 @@ protected:
             //  Check requested field averages are valid, populate field lists
             void initialize();
 
+            //- Restart averaging for restartOnOutput
+            void restart();
+
             //- Add mean average field to database
             template<class Type>
             void addMeanFieldType(const label fieldI);

src/postProcessing/functionObjects/field/fieldAverage/fieldAverage/fieldAverageTemplates.C

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2011-2015 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2016 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -66,7 +66,7 @@ void Foam::fieldAverage::addMeanFieldType(const label fieldI)
                     meanFieldName,
                     obr_.time().timeName(obr_.time().startTime().value()),
                     obr_,
-                    resetOnOutput_
+                    restartOnOutput_
                   ? IOobject::NO_READ
                   : IOobject::READ_IF_PRESENT,
                     IOobject::NO_WRITE
@@ -136,7 +136,7 @@ void Foam::fieldAverage::addPrime2MeanFieldType(const label fieldI)
                     prime2MeanFieldName,
                     obr_.time().timeName(obr_.time().startTime().value()),
                     obr_,
-                    resetOnOutput_
+                    restartOnOutput_
                   ? IOobject::NO_READ
                   : IOobject::READ_IF_PRESENT,
                     IOobject::NO_WRITE

tutorials/discreteMethods/dsmcFoam/freeSpacePeriodic/system/controlDict

@@ -54,7 +54,6 @@ functions
         type            fieldAverage;
         functionObjectLibs ( "libfieldFunctionObjects.so" );
         outputControl   outputTime;
-        resetOnOutput   off;
 
         fields
         (

tutorials/discreteMethods/dsmcFoam/freeSpaceStream/system/controlDict

@@ -54,7 +54,7 @@ functions
         type            fieldAverage;
         functionObjectLibs ( "libfieldFunctionObjects.so" );
         outputControl   outputTime;
-        resetOnOutput   off;
+        restartOnOutput   off;
 
         fields
         (

tutorials/discreteMethods/dsmcFoam/supersonicCorner/system/controlDict

@@ -54,7 +54,6 @@ functions
         type            fieldAverage;
         functionObjectLibs ( "libfieldFunctionObjects.so" );
         outputControl   outputTime;
-        resetOnOutput   off;
 
         fields
         (

tutorials/discreteMethods/dsmcFoam/wedge15Ma5/system/controlDict

@@ -54,7 +54,6 @@ functions
         type            fieldAverage;
         functionObjectLibs ( "libfieldFunctionObjects.so" );
         outputControl   outputTime;
-        resetOnOutput   off;
 
         fields
         (