ENH: adding total isentropic pressure option

src/functionObjects/field/pressure/pressure.C

@@ -27,6 +27,7 @@ License
 
 #include "pressure.H"
 #include "volFields.H"
+#include "fluidThermo.H"
 #include "addToRunTimeSelectionTable.H"
 
 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
@@ -51,6 +52,10 @@ Foam::word Foam::functionObjects::pressure::resultName() const
     {
         rName = "total(" + fieldName_ + ")";
     }
+    else if (calcIsen_)
+    {
+        rName = "totalIsen(" + fieldName_ + ")";
+    }
     else
     {
         rName = "static(" + fieldName_ + ")";
@@ -145,6 +150,21 @@ Foam::tmp<Foam::volScalarField> Foam::functionObjects::pressure::pDyn
             tp
           + rhoScale(p, 0.5*magSqr(lookupObject<volVectorField>(UName_)));
     }
+    else if (calcIsen_)
+    {
+        const fluidThermo* thermoPtr =
+            p.mesh().lookupObjectPtr<fluidThermo>(basicThermo::dictName);
+
+        const volScalarField gamma(thermoPtr->gamma());
+
+        const volScalarField Mb
+        (
+            mag(lookupObject<volVectorField>(UName_))
+           /sqrt(gamma*tp.ref()/thermoPtr->rho())
+        );
+
+        return tp.ref()*(pow(1 + (gamma-1)/2*sqr(Mb), gamma/(gamma-1)));
+    }
     else
     {
         return std::move(tp);
@@ -220,6 +240,7 @@ Foam::functionObjects::pressure::pressure
     UName_("U"),
     rhoName_("rho"),
     calcTotal_(false),
+    calcIsen_(false),
     pRef_(0),
     calcCoeff_(false),
     pInf_(0),
@@ -252,6 +273,8 @@ bool Foam::functionObjects::pressure::read(const dictionary& dict)
         rhoInfInitialised_ = true;
     }
 
+    calcIsen_ = dict.lookupOrDefault<bool>("calcIsen", false);
+
     dict.readEntry("calcTotal", calcTotal_);
     if (calcTotal_)
     {

src/functionObjects/field/pressure/pressure.H

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2016 OpenCFD Ltd.
+    \\  /    A nd           | Copyright (C) 2016-2019 OpenCFD Ltd.
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
                             | Copyright (C) 2012-2016 OpenFOAM Foundation
@@ -41,6 +41,10 @@ Description
         \f[
             p_0 = p_{ref} + p + 0.5 \rho |U|^2
         \f]
+    - isentropic pressure
+        \f[
+            p_iso = p*(1 + ((gamma-1)*M^2)/2)^(gamma/(gamma - 1))
+        \f]
     - static pressure coefficient
         \f[
             Cp = \frac{p - p_{\inf}}{0.5 \rho_{\inf} |U_{\inf}|^2}
@@ -61,6 +65,7 @@ Description
         p           | Pressure [Pa]
         p_0         | Total pressure [Pa]
         p_{ref}     | Reference pressure level [Pa]
+        p_iso       | Total isentropic pressure
         Cp          | Pressure coefficient
         Cp_0        | Total pressure coefficient
     \endvartable
@@ -71,11 +76,12 @@ Description
 
     The modes of operation are:
     \table
-        Mode                        | calcTotal | calcCoeff
+        Mode                        | calcTotal | calcCoeff | calcIsen
-        Static pressure             | no        | no
+        Static pressure             | no        | no        | no
-        Total pressure              | yes       | no
+        Total pressure              | yes       | no        | no
-        Pressure coefficient        | no        | yes
+        Pressure coefficient        | no        | yes       | no
-        Total pressure coefficient  | yes       | yes
+        Total pressure coefficient  | yes       | yes       | no
+        Total isentropic pressure   | no        | no        | yes
     \endtable
 
 Usage
@@ -100,6 +106,7 @@ Usage
         rho          | Name of the density field   | no         | rho
         result       | Name of the resulting field | no         | derived from p
         calcTotal    | Calculate total coefficient | yes        |
+        calcIsen     | Calculate total isentropic  | no         | no
         pRef         | Reference pressure for total pressure | no | 0
         calcCoeff    | Calculate pressure coefficient | yes     |
         pInf         | Freestream pressure for coefficient calculation | no |
@@ -152,6 +159,9 @@ class pressure
             //- Flag to calculate total pressure
             bool calcTotal_;
 
+            //- Flag to calculate identropic total pressure
+            bool calcIsen_;
+
             //- Reference pressure level
             scalar pRef_;