STYLE: electricPotential: simplify read function

- change 'fieldName' to 'Vname' for better clarity

src/functionObjects/solvers/electricPotential/electricPotential.C

@@ -201,11 +201,11 @@ Foam::functionObjects::electricPotential::electricPotential
             )
         )
     ),
-    fieldName_
+    Vname_
     (
         dict.getOrDefault<word>
         (
-            "field",
+            "V",
             IOobject::scopedName(typeName, "V")
         )
     ),
@@ -216,7 +216,7 @@ Foam::functionObjects::electricPotential::electricPotential
 
     // Force creation of transported field so any BCs using it can
     // look it up
-    volScalarField& eV = getOrReadField(fieldName_);
+    volScalarField& eV = getOrReadField(Vname_);
     eV.correctBoundaryConditions();
 }
 
@@ -225,8 +225,11 @@ Foam::functionObjects::electricPotential::electricPotential
 
 bool Foam::functionObjects::electricPotential::read(const dictionary& dict)
 {
-    if (fvMeshFunctionObject::read(dict))
+    if (!fvMeshFunctionObject::read(dict))
     {
+        return false;
+    }
+
     Log << type() << " read: " << name() << endl;
 
     dict.readIfPresent("sigma", sigma_);
@@ -306,9 +309,6 @@ bool Foam::functionObjects::electricPotential::read(const dictionary& dict)
         }
     }
 
-        return true;
-    }
-
     return false;
 }
 
@@ -318,11 +318,11 @@ bool Foam::functionObjects::electricPotential::execute()
     Log << type() << " execute: " << name() << endl;
 
     tmp<volScalarField> tsigma = this->sigma();
-    const volScalarField& sigma = tsigma();
+    const auto& sigma = tsigma();
 
-    volScalarField& eV = getOrReadField(fieldName_);
+    volScalarField& eV = getOrReadField(Vname_);
 
-    for (label i = 1; i <= nCorr_; ++i)
+    for (int i = 1; i <= nCorr_; ++i)
     {
         fvScalarMatrix eVEqn
         (
@@ -343,10 +343,10 @@ bool Foam::functionObjects::electricPotential::execute()
 bool Foam::functionObjects::electricPotential::write()
 {
     Log << type() << " write: " << name() << nl
-        << tab << fieldName_
+        << tab << Vname_
         << endl;
 
-    volScalarField& eV = getOrReadField(fieldName_);
+    volScalarField& eV = getOrReadField(Vname_);
 
     if (writeDerivedFields_)
     {

src/functionObjects/solvers/electricPotential/electricPotential.H

@@ -118,9 +118,9 @@ Usage
             }
 
         // Optional entries
-        nCorr                 <label>;
+        nCorr                 <int>;
         writeDerivedFields    <bool>;
-        fieldName             <word>;
+        V                     <word>;
 
         // Inherited entries
         ...
@@ -134,9 +134,9 @@ Usage
       libs      | Library name: solverFunctionObjects | word | yes  | -
       sigma     | Isotropic electrical conductivity of phase | scalar | yes | -
       epsilonr  | Isotropic relative permittivity of phase   | scalar | no  | -
-      nCorr     | Number of corrector iterations     | label | no   | 1
+      nCorr     | Number of corrector iterations      | int  | no   | 1
       writeDerivedFields | Flag to write extra fields | bool | no   | false
-      fieldName | Name of operand field   | word | no | electricPotential:V
+      V    | Name of electric potential field | word | no | electricPotential:V
     \endtable
 
     The inherited entries are elaborated in:
@@ -199,11 +199,11 @@ class electricPotential
         //- Isotropic relative permittivity of a single phase
         dimensionedScalar epsilonr_;
 
-        //- Name of the operand field
+        //- Name of electric potential field
-        word fieldName_;
+        word Vname_;
 
         //- Number of corrector iterations
-        label nCorr_;
+        int nCorr_;
 
         //- Flag to write derived fields of
         //- electric field, current density and free-charge density