volumetricFlowRateTriSurface: Corrected pre-configuration, and added an example

A volumetric flow rate through a tri-surface can now be obtained using
the volumetricFlowRateTriSurface preconfigured function object, using
the following entry in system/controlDict:

    fuctions
    {
        #includeFunc "volumetricFlowRateTriSurface(name=surface.stl)"
    }

Where "surface.stl" is a tri-surface file in the constant/triSurface
directory. An example of this has been added to the
incompressible/pimpleFoam/RAS/impeller tutorial case.

Note that when possible, it is preferable to use the flowRatePatch or
flowRateFaceZone functions, as these make direct use of the flux and
therefore report a value that is exactly that computed by the solver.
volumetricFlowRateTriSurface, by contrast, does interpolation of the
velocity field which introduces error.

In addition, a minor fix has been made to the underlying
surfaceFieldValue function object so that it does not need a zone/set
name when values on a searchable surface are requested.

etc/caseDicts/postProcessing/flowRate/volumetricFlowRateTriSurface

@@ -13,8 +13,8 @@ Description
 
 \*---------------------------------------------------------------------------*/
 
-triSurface <triSurfaceFile>;
+name    <triSurfaceFileName>;
 
-#includeEtc "caseDicts/postProcessing/flowRate/volFlowRateSurface.cfg"
+#includeEtc "caseDicts/postProcessing/flowRate/volumetricFlowRateTriSurface.cfg"
 
 // ************************************************************************* //

etc/caseDicts/postProcessing/flowRate/volumetricFlowRateTriSurface.cfg

@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 \*---------------------------------------------------------------------------*/
 
-#includeEtc "caseDicts/postProcessing/surfaceFieldValue/surfaceRegion.cfg"
+#includeEtc "caseDicts/postProcessing/surfaceFieldValue/triSurfaceRegion.cfg"
 
 fields (U);
 operation areaNormalIntegrate;

etc/caseDicts/postProcessing/surfaceFieldValue/triSurfaceRegion.cfg

@@ -13,7 +13,7 @@ regionType sampledSurface;
 sampledSurfaceDict
 {
     type        triSurfaceMesh;
-    surface     $triSurface;
+    surface     $name;
     source      cells;
     interpolate true;
 }

src/functionObjects/field/fieldValues/surfaceFieldValue/surfaceFieldValue.C

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2011-2020 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2021 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -426,23 +426,24 @@ void Foam::functionObjects::fieldValues::surfaceFieldValue::initialise
     const dictionary& dict
 )
 {
-    dict.lookup("name") >> regionName_;
-
     switch (regionType_)
     {
         case regionTypes::faceZone:
         {
+            dict.lookup("name") >> regionName_;
             setFaceZoneFaces();
             break;
         }
         case regionTypes::patch:
         {
+            dict.lookup("name") >> regionName_;
             setPatchFaces();
             break;
         }
         case regionTypes::sampledSurface:
         {
             sampledSurfaceFaces(dict);
+            regionName_ = surfacePtr_().name();
             break;
         }
         default:

tutorials/incompressible/pimpleFoam/RAS/impeller/system/controlDict

@@ -49,5 +49,12 @@ adjustTimeStep  yes;
 
 maxCo           1.0;
 
+functions
+{
+    #includeFunc "flowRatePatch(name=inlet)"
+    #includeFunc "flowRatePatch(name=outlet)"
+    #includeFunc "volumetricFlowRateTriSurface(name=surface0.stl)"
+    #includeFunc "volumetricFlowRateTriSurface(name=surface1.stl)"
+}
 
 // ************************************************************************* //