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Implemented more partial derivatives, still need a proper mapping of the additional quantities.

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This commit is contained in:
Jorrit Wronski
2015-11-15 16:33:31 +01:00
parent 45aa71f29d
commit 264076d8cd
3 changed files with 39 additions and 24 deletions
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23
Web/fluid_properties/Incompressibles.rst
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@@ -155,25 +155,30 @@ corresponds to the new mixture syntax in CoolProp v5.
Partial Derivatives
-------------------
A limited subset of partial derivatives is available for the incompressible fluids. As of
October 2015, the following inputs are supported by the ``PropsSI`` function:
A limited subset of partial derivatives is available for the incompressible fluids. Currently,
the following inputs are supported by the ``PropsSI`` function:
:math:`\left( \partial \rho / \partial p \right)_{T,x}=0`,
:math:`\left( \partial \rho / \partial h \right)_{p,x}`,
:math:`\left( \partial \rho / \partial s \right)_{p,x}`,
:math:`\left( \partial \rho / \partial T \right)_{p,x}`,
:math:`\left( \partial h / \partial p \right)_{T,x}`,
:math:`\left( \partial h / \partial s \right)_{T,x}`,
:math:`\left( \partial h / \partial T \right)_{p,x}`,
:math:`\left( \partial s / \partial p \right)_{T,x}`,
:math:`\left( \partial s / \partial T \right)_{p,x}`,
:math:`\left( \partial h / \partial T \right)_{p,x}`,
:math:`\left( \partial s / \partial p \right)_{T,x}` and
:math:`\left( \partial h / \partial p \right)_{T,x}`.
and their inverse functions.
Note that all partial derivatives require a constant concentration, which is denoted by the
``x``, but this ``x`` is not included in the derivative string notation for ``PropsSI``:
:math:`x`, but this :math:`x` is not included in the derivative string notation for ``PropsSI``:
:math:`\left( \partial \rho / \partial T \right)_{p,x}` translates to ``d(Dmass)/d(T)|P``.
.. note::
You can compute other properties from the partial derivatives available. At this point, not
You can calculate other properties from the partial derivatives available. At this point, not
all derived properties have been implemented even though some of them can be computed like the
isobaric expansion coefficient, which would be :math:`-1/\rho \left( \partial \rho / \partial T \right)_{p,x}`.
isobaric expansion coefficient, which would be :math:`-\left( \partial \rho / \partial T \right)_{p,x}/\rho`.
For more general information on the partial derivatives, please have a look at the
:ref:`documentation<_partial_derivatives_high_level>` for the high level interface.
:ref:`documentation<partial_derivatives_high_level>` for the high level interface.
.. _FittingReports:

28
src/Backends/Incompressible/IncompressibleBackend.cpp
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@@ -482,17 +482,27 @@ CoolPropDbl IncompressibleBackend::raw_calc_smass(double T, double p, double x){
/// Calculate the first partial derivative for the desired derivative
CoolPropDbl IncompressibleBackend::calc_first_partial_deriv(parameters Of, parameters Wrt, parameters Constant){
// TODO: Can this be accelerated?
if ( (Of==iDmass) && (Wrt==iT) && (Constant==iP) ) return drhodTatPx();
if ( (Of==iSmass) && (Wrt==iT) && (Constant==iP) ) return dsdTatPx();
if ( (Of==iHmass) && (Wrt==iT) && (Constant==iP) ) return dhdTatPx();
if ( (Of==iDmass) && (Wrt==iP) ) return 0.0; // incompressible!
if ( (Of==iDmass) && (Wrt==iHmass) && (Constant==iP) ) return drhodTatPx()/dhdTatPx();
if ( (Of==iHmass) && (Wrt==iDmass) && (Constant==iP) ) return dhdTatPx()/drhodTatPx();
if ( (Of==iDmass) && (Wrt==iSmass) && (Constant==iP) ) return drhodTatPx()/dsdTatPx();
if ( (Of==iSmass) && (Wrt==iDmass) && (Constant==iP) ) return dsdTatPx()/drhodTatPx();
if ( (Of==iDmass) && (Wrt==iT) && (Constant==iP) ) return drhodTatPx();
if ( (Of==iT) && (Wrt==iDmass) && (Constant==iP) ) return 1.0/drhodTatPx();
//
if ( (Of==iHmass) && (Wrt==iP) && (Constant==iT) ) return dhdpatTx();
if ( (Of==iP) && (Wrt==iHmass) && (Constant==iT) ) return 1.0/dhdpatTx();
if ( (Of==iHmass) && (Wrt==iSmass) && (Constant==iT) ) return dhdpatTx()/dsdpatTx();
if ( (Of==iSmass) && (Wrt==iHmass) && (Constant==iT) ) return dsdpatTx()/dhdpatTx();
if ( (Of==iHmass) && (Wrt==iT) && (Constant==iP) ) return dhdTatPx();
if ( (Of==iT) && (Wrt==iHmass) && (Constant==iP) ) return 1.0/dhdTatPx();
//
if ( (Of==iSmass) && (Wrt==iP) && (Constant==iT) ) return dsdpatTx();
if ( (Of==iP) && (Wrt==iSmass) && (Constant==iT) ) return 1.0/dsdpatTx();
if ( (Of==iSmass) && (Wrt==iT) && (Constant==iP) ) return dsdTatPx();
if ( (Of==iT) && (Wrt==iSmass) && (Constant==iP) ) return 1.0/dsdTatPx();
//if ( (Of==iHmass) && (Wrt==iP) && (Constant==iT) ) return dsdTatPxdT();
//if ( (Of==iHmass) && (Wrt==iP) && (Constant==iT) ) return dhdTatPxdT();
if ( (Of==iSmass) && (Wrt==iP) && (Constant==iT) ) return dsdpatTx();
if ( (Of==iHmass) && (Wrt==iP) && (Constant==iT) ) return dhdpatTx();
if ( (Of==iDmass) && (Wrt==iHmass) && (Constant==iP) ) return drhodTatPx()/dhdTatPx();
if ( (Of==iDmass) && (Wrt==iP) ) return 0.0; // incompressible!
throw ValueError("Incompressible fluids only support a limited subset of partial derivatives.");
}

12
src/Backends/Incompressible/IncompressibleBackend.h
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@@ -214,22 +214,22 @@ protected:
/// Partial derivative of enthalpy with respect to temperature at constant pressure and composition
double calc_dhdTatPx (double T, double p, double x){return fluid->c(T,p,x);};
/// Partial derivative of entropy
// with respect to temperature at constant pressure and composition
// integrated in temperature
/// with respect to temperature at constant pressure and composition
/// integrated in temperature
double calc_dsdTatPxdT(double T, double p, double x){return fluid->dsdTatPxdT(T,p,x);};
/// Partial derivative of enthalpy
// with respect to temperature at constant pressure and composition
// integrated in temperature
/// with respect to temperature at constant pressure and composition
/// integrated in temperature
double calc_dhdTatPxdT(double T, double p, double x){return fluid->dhdTatPxdT(T,p,x);};
/* Other useful derivatives
*/
/// Partial derivative of entropy with respect to pressure at constant temperature and composition
// \f[ \left( \frac{\partial s}{\partial p} \right)_T = - \left( \frac{\partial v}{\partial T} \right)_p = \rho^{-2} \left( \frac{\partial \rho}{\partial T} \right)_p \right) \f]
/// \f[ \left( \frac{\partial s}{\partial p} \right)_T = - \left( \frac{\partial v}{\partial T} \right)_p = \rho^{-2} \left( \frac{\partial \rho}{\partial T} \right)_p \right) \f]
double calc_dsdpatTx (double rho, double drhodTatPx);
/// Partial derivative of enthalpy with respect to pressure at constant temperature and composition
// \f[ \left( \frac{\partial h}{\partial p} \right)_T = v - T \left( \frac{\partial v}{\partial T} \right)_p = \rho^{-1} \left( 1 + T \rho^{-1} \left( \frac{\partial \rho}{\partial T} \right)_p \right) \f]
/// \f[ \left( \frac{\partial h}{\partial p} \right)_T = v - T \left( \frac{\partial v}{\partial T} \right)_p = \rho^{-1} \left( 1 + T \rho^{-1} \left( \frac{\partial \rho}{\partial T} \right)_p \right) \f]
double calc_dhdpatTx (double T, double rho, double drhodTatPx);