Most of thermodynamic properties calculated in yaeos heavily depend on different kind of models and their respective derivatives. Since obtaining the derivatives of complex models can be a tedious and error-prone task. We provide two different ways of getting them automatically (in some cases with some performance-cost), but there is also the possibility of using analytical obtained expressions instead.

The calculation of thermodynamic properties heavily depends on

On yaeos there are three different ways of adding your own model:W

Residual Helmholtz models

Residual Helmholtz models are the basis to obtain the residual properties.

The main basis in yaeos to define a new object that extends the abstract typecalled` ArModel. Which enforces the expected functionality of this kind of models.

use yaeos, only: ArModel

type, extends(ArModel) :: MyNewModel
end type

The definition of an ArModel expects that two procedures are defined:

• abs_residual_helmholtz: Procedure to calculate residual Helmholtz energy and it’s derivatives
• abs_volume_initializer: Volume initializer to find a liquid root, given a pressure and temperature.

use yaeos, only: ArModel

type, extends(ArModel) :: MyNewModel
contains
    procedure :: residual_helmholtz => an_Ar_implementation
    procedure :: volume_initializer => an_v0_implementation
end type

Satisfying those requirements, our model will be ready to make calculations!

use yaeos, only: pressure
use my_model, only: MyNewModel

type(MyNewModel) :: model

! Assuming model parameters are set-up
call pressure(model, n, V, T, P)