fvConstraints, fvModels: zeroDimensionalFixedPressure

A constraint and a model have been added, both called
zeroDimensionalFixedPressure, that together act to maintain a pressure
constraint in a zero-dimensional case. These must be used
simultaneously. The desired pressure can be specified as a time-varying
Function1.

These replace the pressureConstraintSource, which has been removed.

The new classes operate by obtaining the residual of the complete
pressure equation, and using that to calculate the mass or volume
sources that need adding to the fluid in order to maintain the
constraint. This process is far more convergent than the previous
approach, it does not require the fluid to have a certain thermodynamic
model, and it is generalisable to multiphase.

This functionality requires only minimal specification. The constraint
contains all the settings and should be specified in
system/fvConstraints as follows:

    zeroDimensionalFixedPressure1
    {
        type            zeroDimensionalFixedPressure;

        // Name of the pressure field, default = p
        //p               p;

        // Name of the density field, default = rho
        //rho             rho;

        // Constant pressure value
        pressure        1e5;

        //// Time-varying pressure value
        //pressure
        //{
        //    type            table;
        //    values
        //    (
        //        (0 1e5)
        //        (1 1e5)
        //        (1.1 1.4e5)
        //        (10 1.4e5)
        //    );
        //}
    }

The model is then added to constant/fvModels, and requires no settings:

    zeroDimensionalFixedPressure1
    {
        type            zeroDimensionalFixedPressure;
    }

tutorials/modules/multicomponentFluid/nc7h16/0/p

@@ -16,7 +16,7 @@ FoamFile
 
 dimensions      [1 -1 -2 0 0 0 0];
 
-internalField   uniform 5.06625e+06;
+internalField   uniform 5.06625e6;
 
 boundaryField   {}
 

tutorials/modules/multicomponentFluid/nc7h16/constant/fvModels

@@ -14,10 +14,9 @@ FoamFile
 }
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
-pressureConstraintSource1
+zeroDimensionalFixedPressure1
 {
-    type            pressureConstraintSource;
-    p               1.36789e6;
+    type            zeroDimensionalFixedPressure;
 }
 
 //************************************************************************* //

tutorials/modules/multicomponentFluid/nc7h16/system/fvConstraints

@@ -0,0 +1,24 @@
+/*--------------------------------*- C++ -*----------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     | Website:  https://openfoam.org
+    \\  /    A nd           | Version:  dev
+     \\/     M anipulation  |
+\*---------------------------------------------------------------------------*/
+FoamFile
+{
+    format      ascii;
+    class       dictionary;
+    location    "system";
+    object      fvConstraints;
+}
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+zeroDimensionalFixedPressure1
+{
+    type            zeroDimensionalFixedPressure;
+
+    pressure        5.06625e6;
+}
+
+// ************************************************************************* //

tutorials/modules/multicomponentFluid/nc7h16/system/fvSolution

@@ -47,7 +47,7 @@ solvers
 PIMPLE
 {
     nOuterCorrectors 1;
-    nCorrectors     2;
+    nCorrectors     1;
     nNonOrthogonalCorrectors 0;
 }