ENH: use Zero when zero-initializing types

- makes the intent clearer and avoids the need for additional
  constructor casting. Eg,

      labelList(10, Zero)    vs.  labelList(10, 0)
      scalarField(10, Zero)  vs.  scalarField(10, scalar(0))
      vectorField(10, Zero)  vs.  vectorField(10, vector::zero)

src/functionObjects/field/extractEulerianParticles/eulerianParticle/eulerianParticle.C

@@ -33,8 +33,8 @@ using namespace Foam::constant;
 Foam::functionObjects::eulerianParticle::eulerianParticle()
 :
     faceIHit(-1),
-    VC(vector::zero),
-    VU(vector::zero),
+    VC(Zero),
+    VU(Zero),
     V(0),
     time(0)
 {}

src/functionObjects/field/fluxSummary/fluxSummary.C

@@ -721,8 +721,8 @@ bool Foam::functionObjects::fluxSummary::surfaceModeWrite()
 
         const boolList& flips = faceFlip_[surfi];
 
-        scalar phiPos = scalar(0);
-        scalar phiNeg = scalar(0);
+        scalar phiPos(0);
+        scalar phiNeg(0);
 
         tmp<scalarField> tphis = phi & s.Sf();
         const scalarField& phis = tphis();
@@ -1047,9 +1047,9 @@ bool Foam::functionObjects::fluxSummary::write()
         const labelList& facePatchID = facePatchID_[zonei];
         const boolList&  faceFlips = faceFlip_[zonei];
 
-        scalar phiPos = scalar(0);
-        scalar phiNeg = scalar(0);
-        scalar phif = scalar(0);
+        scalar phiPos(0);
+        scalar phiNeg(0);
+        scalar phif(0);
 
         forAll(faceID, i)
         {

src/functionObjects/field/heatTransferCoeff/heatTransferCoeffModels/ReynoldsAnalogy/ReynoldsAnalogy.C

@@ -169,7 +169,7 @@ Foam::heatTransferCoeffModels::ReynoldsAnalogy::Cf() const
 
     forAll(Cf, patchi)
     {
-        Cf.set(patchi, new Field<scalar>(Ubf[patchi].size(), 0));
+        Cf.set(patchi, new Field<scalar>(Ubf[patchi].size(), Zero));
     }
 
     const volSymmTensorField R(devReff());
@@ -203,7 +203,7 @@ Foam::heatTransferCoeffModels::ReynoldsAnalogy::ReynoldsAnalogy
 :
     heatTransferCoeffModel(dict, mesh, TName),
     UName_("U"),
-    URef_(vector::zero),
+    URef_(Zero),
     rhoName_("rho"),
     rhoRef_(0.0),
     CpName_("Cp"),

src/functionObjects/field/histogram/histogram.C

@@ -193,8 +193,8 @@ bool Foam::functionObjects::histogram::write()
         x += delta;
     }
 
-    scalarField dataNormalized(nBins_, 0);
-    labelField dataCount(nBins_, 0);
+    scalarField dataNormalized(nBins_, Zero);
+    labelField dataCount(nBins_, Zero);
     const scalarField& V = mesh_.V();
 
     forAll(field, celli)

src/functionObjects/field/pressure/pressure.C

@@ -255,7 +255,7 @@ bool Foam::functionObjects::pressure::read(const dictionary& dict)
     dict.readEntry("calcTotal", calcTotal_);
     if (calcTotal_)
     {
-        pRef_ = dict.lookupOrDefault<scalar>("pRef", 0.0);
+        pRef_ = dict.lookupOrDefault<scalar>("pRef", 0);
     }
 
     dict.readEntry("calcCoeff", calcCoeff_);

src/functionObjects/field/reference/reference.C

@@ -74,7 +74,7 @@ Foam::functionObjects::reference::reference
 :
     fieldExpression(name, runTime, dict),
     localDict_(dict),
-    position_(point::zero),
+    position_(Zero),
     positionIsSet_(false),
     celli_(-1),
     interpolationScheme_("cell"),

src/functionObjects/field/regionSizeDistribution/regionSizeDistribution.C

@@ -239,7 +239,7 @@ void Foam::functionObjects::regionSizeDistribution::writeGraphs
     if (Pstream::master())
     {
         // Calculate per-bin average
-        scalarField binSum(nBins_, 0.0);
+        scalarField binSum(nBins_, Zero);
         forAll(sortedField, i)
         {
             binSum[indices[i]] += sortedField[i];
@@ -248,7 +248,7 @@ void Foam::functionObjects::regionSizeDistribution::writeGraphs
         scalarField binAvg(divide(binSum, binCount));
 
         // Per bin deviation
-        scalarField binSqrSum(nBins_, 0.0);
+        scalarField binSqrSum(nBins_, Zero);
         forAll(sortedField, i)
         {
             binSqrSum[indices[i]] += Foam::sqr(sortedField[i]);
@@ -694,7 +694,7 @@ bool Foam::functionObjects::regionSizeDistribution::write()
             )
         );
 
-        vectorField centroids(sortedVols.size(), vector::zero);
+        vectorField centroids(sortedVols.size(), Zero);
 
         // Check if downstream bins are calculated
         if (isoPlanes_)
@@ -748,7 +748,7 @@ bool Foam::functionObjects::regionSizeDistribution::write()
                 }
             }
 
-            scalarField binDownCount(nDownstreamBins_, 0.0);
+            scalarField binDownCount(nDownstreamBins_, Zero);
             forAll(distToPlane, i)
             {
                 if (downstreamIndices[i] != -1)
@@ -815,7 +815,7 @@ bool Foam::functionObjects::regionSizeDistribution::write()
         }
 
         // Calculate the counts per diameter bin
-        scalarField binCount(nBins_, 0.0);
+        scalarField binCount(nBins_, Zero);
         forAll(sortedDiameters, i)
         {
             binCount[indices[i]] += 1.0;

src/functionObjects/field/setFlow/setFlow.C

@@ -115,7 +115,7 @@ Foam::functionObjects::setFlow::setFlow
     mode_(modeType::FUNCTION),
     reverseTime_(VGREAT),
     scalePtr_(nullptr),
-    origin_(vector::zero),
+    origin_(Zero),
     R_(tensor::I),
     omegaPtr_(nullptr),
     velocityPtr_(nullptr)

src/functionObjects/field/stabilityBlendingFactor/stabilityBlendingFactor.C

@@ -492,10 +492,10 @@ Foam::functionObjects::stabilityBlendingFactor::stabilityBlendingFactor
     ),
 
     tolerance_(0.001),
-    error_(mesh_.nCells(), 0.0),
-    errorIntegral_(mesh_.nCells(), 0.0),
-    oldError_(mesh_.nCells(), 0.0),
-    oldErrorIntegral_(mesh_.nCells(), 0.0),
+    error_(mesh_.nCells(), Zero),
+    errorIntegral_(mesh_.nCells(), Zero),
+    oldError_(mesh_.nCells(), Zero),
+    oldErrorIntegral_(mesh_.nCells(), Zero),
     P_(dict.lookupOrDefault<scalar>("P", 3)),
     I_(dict.lookupOrDefault<scalar>("I", 0.0)),
     D_(dict.lookupOrDefault<scalar>("D", 0.25))

src/functionObjects/forces/forces/forces.C

@@ -847,7 +847,7 @@ bool Foam::functionObjects::forces::read(const dictionary& dict)
         }
 
         // Reference pressure, 0 by default
-        pRef_ = dict.lookupOrDefault<scalar>("pRef", 0.0);
+        pRef_ = dict.lookupOrDefault<scalar>("pRef", 0);
     }
 
     coordSys_.clear();

src/functionObjects/randomProcesses/energySpectrum/energySpectrum.C

@@ -87,7 +87,7 @@ void Foam::functionObjects::energySpectrum::calcAndWriteSpectrum
     }
 
     Log << "Computing energy spectrum" << endl;
-    scalarField E(nMax, 0);
+    scalarField E(nMax, Zero);
     const scalarField Ec(0.5*magSqr(Uf));
     forAll(C, celli)
     {

src/functionObjects/utilities/residuals/residuals.C

@@ -101,7 +101,7 @@ void Foam::functionObjects::residuals::createField(const word& fieldName)
                     IOobject::NO_READ,
                     IOobject::NO_WRITE
                 ),
-                Field<scalar>(mesh_.nCells(), scalar(0))
+                Field<scalar>(mesh_.nCells(), Zero)
             );
 
         fieldPtr->store();

src/functionObjects/utilities/thermoCoupleProbes/thermoCoupleProbes.C

@@ -103,13 +103,13 @@ void Foam::functionObjects::thermoCoupleProbes::derivatives
     scalarField& dydx
 ) const
 {
-    scalarField G(y.size(), 0.0);
-    scalarField Tc(y.size(), 0.0);
-    scalarField Uc(y.size(), 0.0);
-    scalarField rhoc(y.size(), 0.0);
-    scalarField muc(y.size(), 0.0);
-    scalarField Cpc(y.size(), 0.0);
-    scalarField kappac(y.size(), 0.0);
+    scalarField G(y.size(), Zero);
+    scalarField Tc(y.size(), Zero);
+    scalarField Uc(y.size(), Zero);
+    scalarField rhoc(y.size(), Zero);
+    scalarField muc(y.size(), Zero);
+    scalarField Cpc(y.size(), Zero);
+    scalarField kappac(y.size(), Zero);
 
     if (radiationFieldName_ != "none")
     {