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========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration | Website: https://openfoam.org
\\ / A nd | Copyright (C) 2012-2025 OpenFOAM Foundation
\\/ M anipulation |
-------------------------------------------------------------------------------
License
This file is part of OpenFOAM.
OpenFOAM is free software: you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
You should have received a copy of the GNU General Public License
along with OpenFOAM. If not, see <http://www.gnu.org/licenses/>.
Class
Foam::functionObjects::pressure
Description
Includes tools to manipulate the pressure into different forms.
These currently include:
- static pressure
\f[
p = \rho p_k
\f]
- total pressure
\f[
p_0 = p_{ref} + p + 0.5 \rho |U|^2
\f]
- static pressure coefficient
\f[
Cp = \frac{p - p_{\inf}}{0.5 \rho_{\inf} |U_{\inf}|^2}
\f]
- total pressure coefficient
\f[
Cp_0 = \frac{p_0 - p_{\inf}}{0.5 \rho_{\inf} |U_{\inf}|^2}
\f]
where
\vartable
\rho | Density [kg/m^3]
U | Velocity [m/s]
\rho_{\inf} | Freestream density [kg/m^3]
p_{\inf} | Freestream pressure [Pa]
U_{\inf} | Freestream velocity [m/s]
p_k | Kinematic pressure (p/rho) [m^2/s^2]
p | Pressure [Pa]
p_0 | Total pressure [Pa]
p_{ref} | Reference pressure level [Pa]
Cp | Pressure coefficient
Cp_0 | Total pressure coefficient
\endvartable
The function object will operate on both kinematic (\f$ p_k \f$) and static
pressure (\f$ p \f$) fields, and the result is written as a
volScalarField.
The modes of operation are:
\table
Mode | calcTotal | calcCoeff
Static pressure | no | no
Total pressure | yes | no
Pressure coefficient | no | yes
Total pressure coefficient | yes | yes
\endtable
Example of function object specification to calculate pressure coefficient:
\verbatim
pressure1
{
type pressure;
libs ("libfieldFunctionObjects.so");
...
calcTotal no;
calcCoeff yes;
}
\endverbatim
Usage
\table
Property | Description | Required | Default value
type | type name: pressure | yes |
field | Name of the pressure field | no | p
U | Name of the velocity field | no | U
rho | Name of the density field | no | rho
result | Name of the resulting field | no | derived from p
calcTotal | Calculate total coefficient | yes |
pRef | Reference pressure for total pressure | no | 0
calcCoeff | Calculate pressure coefficient | yes |
pInf | Freestream pressure for coefficient calculation | no |
UInf | Freestream velocity for coefficient calculation | no |
rhoInf | Freestream density for coefficient calculation | no |
\endtable
See also
Foam::functionObjects::fieldExpression
Foam::functionObjects::fvMeshFunctionObject
SourceFiles
pressure.C
\*---------------------------------------------------------------------------*/
#ifndef pressure_functionObject_H
#define pressure_functionObject_H
#include "fieldExpression.H"
#include "volFieldsFwd.H"
#include "dimensionedScalar.H"
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
namespace Foam
{
namespace functionObjects
{
/*---------------------------------------------------------------------------*\
Class pressure Declaration
\*---------------------------------------------------------------------------*/
class pressure
:
public fieldExpression
{
// Private Data
//- Name of velocity field, default is "U"
word UName_;
//- Name of density field, default is "rho"
word rhoName_;
// Total pressure calculation
//- Flag to calculate total pressure
bool calcTotal_;
//- Reference pressure level
scalar pRef_;
// Pressure coefficient calculation
//- Flag to calculate pressure coefficient
bool calcCoeff_;
//- Freestream pressure
scalar pInf_;
//- Freestream velocity
vector UInf_;
//- Freestream density
scalar rhoInf_;
// Private Member Functions
//- Return the name of the derived pressure field
word resultName() const;
//- Multiply the static pressure p by rhoInf if necessary and return
tmp<volScalarField> rhoScale(const volScalarField& p) const;
//- Multiply the given field by rho or rhoInf as appropriate and return
tmp<volScalarField> rhoScale
(
const volScalarField& p,
const tmp<volScalarField>& tsf
) const;
//- Return the reference pressure
tmp<volScalarField> pRef(const tmp<volScalarField>& tp) const;
//- Calculate and return the dynamic pressure
tmp<volScalarField> pDyn
(
const volScalarField& p,
const tmp<volScalarField>& tp
) const;
//- Convert to coeff by applying the freestream dynamic pressure scaling
tmp<volScalarField> coeff(const tmp<volScalarField>& tp) const;
//- Calculate the derived pressure field and return true if successful
virtual bool calc();
public:
//- Runtime type information
TypeName("pressure");
// Constructors
//- Construct from Time and dictionary
pressure
(
const word& name,
const Time& runTime,
const dictionary&
);
//- Destructor
virtual ~pressure();
// Member Functions
//- Read the pressure data
virtual bool read(const dictionary&);
};
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
} // End namespace functionObjects
} // End namespace Foam
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
#endif
// ************************************************************************* //
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