pRef is not required (default 0.0) when calcTotal flag is true.

src/functionObjects/field/pressure/pressure.C

@@ -3,7 +3,7 @@
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
     \\  /    A nd           | Copyright (C) 2012-2016 OpenFOAM Foundation
-     \\/     M anipulation  | Copyright (C) 2016 OpenCFD Ltd.
+     \\/     M anipulation  | Copyright (C) 2016-2017 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -249,7 +249,7 @@ bool Foam::functionObjects::pressure::read(const dictionary& dict)
     dict.lookup("calcTotal") >> calcTotal_;
     if (calcTotal_)
     {
-        dict.lookup("pRef") >> pRef_;
+        pRef_ = dict.lookupOrDefault<scalar>("pRef", 0.0);
     }
 
     dict.lookup("calcCoeff") >> calcCoeff_;