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View Code? Open in Web Editor NEWFeOs - A Framework for Equations of State and Classical Density Functional Theory
License: Other
FeOs - A Framework for Equations of State and Classical Density Functional Theory
License: Other
Having these enums outside of the python
feature makes them usable in other contexts as they can be imported in other Rust libraries without having to compile with python
.
When trying to use the package to simulate hydrogen adsorption with saftvrqmie
, the codes gives the error: "The matrix appears to be singular"
from feos.si import *
from feos.dft import *
from feos.saftvrqmie import *
import matplotlib.pyplot as plt
parameters= SaftVRQMieParameters.from_json(
substances=['hydrogen'],
pure_path='.../parameters/saftvrqmie/hammer2023.json')
func = HelmholtzEnergyFunctional.saftvrqmie(parameters, FMTVersion.WhiteBear)
temp = 77*KELVIN
psize= 200*ANGSTROM
solver = DFTSolver().picard_iteration(tol=1e-5, beta=0.05).anderson_mixing()
potential = ExternalPotential.LJ93(3.0, 100.0, 0.08)
bulk = State(func, temp, pressure=30*BAR)
porex = Pore1D(Geometry.Cartesian, psize, potential).initialize(bulk).solve(solver)
plt.plot(porex.z/(ANGSTROM), (porex.density*(METER**3/MOL)/1000).T)
The error is:
Cell In [20], line 9
6 potential = ExternalPotential.LJ93(3.0, 100.0, 0.08)
8 bulk = State(func, temp, pressure=30*BAR)
----> 9 porex = Pore1D(Geometry.Cartesian, psize, potential).initialize(bulk).solve(solver)
11 plt.plot(porex.z/(ANGSTROM), (porex.density*(METER**3/MOL)/1000).T)
13 plt.xlabel(r"$z$ / A")
RuntimeError: The matrix appears to be singular.
When I try with a bigger pore (300 A) it runs with no problems, and if I try an even smaller pore the error changes to:
Cell In [21], line 9
6 potential = ExternalPotential.LJ93(3.0, 100.0, 0.08)
8 bulk = State(func, temp, pressure=30*BAR)
----> 9 porex = Pore1D(Geometry.Cartesian, psize, potential).initialize(bulk).solve(solver)
11 plt.plot(porex.z/(ANGSTROM), (porex.density*(METER**3/MOL)/1000).T)
13 plt.xlabel(r"$z$ / A")
RuntimeError: `Picard Iteration` encountered illegal values during the iteration.
I also tried the same configuration using ´pcsaft´ and had no issues for any pore sizes. Could you please look into this errors?
DQVariants
appears in the pc_saft
constructor but it is currently not exported in the pcsaft
module
When creating a binary phase diagram using PhaseDiagram.binary_vle() the current algorithm is not able to handle systems where a critical point does not exist. This would be the case, for example, for the mixture Ar-NH3 at 298.15 K.
EosError
grew organically while writing core
. For 0.2. we should tidy up this enum a bit and maybe introduce a variant that can be used to report more generic errors.
These points came up in #106
State
object to Python tutorialFollowing #65, we should add benchmarks for possible future performance investigations.
Feel free to add to the list of functions to benchmark.
StateHD
(circumventing closure construction and cache) [#89 ].
Dual64
HyperDual64
Dual3
State
(creating a State
inside benchmark or manually clearing cache) [#89]PhaseEquilibrium
: constructorslto = "thin"
versus lto = true
target-cpu=native
After the changes in feos-dft that should simplify the calculation of pair correlation functions in mixtures, the new interface for pair potentials has not yet been implemented for PC-SAFT and PeTS.
We should add an example notebook on how to use the DataSet
and Estimator
objects to optimize EoS and entropy scaling parameters. Probably when possible changes to the API (due to parallelization?) are done.
Thanks for this package! The SINumber wrapper in python does not seem to have the same methods as the equivalent object in rust (see here). For example, I cannot call .value
on a SINumber. Would it be possible to add that functionality? Below is an example:
from feos.si import *
T = 300*KELVIN
T.value
AttributeError Traceback (most recent call last)
[<ipython-input-55-7f7315c6633b>](https://localhost:8080/#) in <module>
1 from feos.si import *
2 T = 300*KELVIN
----> 3 T.value
AttributeError: 'si_units.SINumber' object has no attribute 'value'
This paper describes a matrix-free Newton algorithm for DFT. The action of the Jacobian on the solution is calculated efficiently using FFT. This can be combined with a linear solver like GMRES that requires only the product of the Jacobian with the current x value.
Convergence could be improved, but as of right now it looks like we would need to implement the GMRES algorithm ourselves.
With version 0.13 of maturin, there are some changes that will crash our current CI workflow for building wheels and recommendations we give in our README.
--no-sdist
is no longer neededcargo-extra-args
is no longer needed. Args to cargo build
work out of the box for maturin build
.Hi,
I was reading of your work, and wanted to read your in-print paper "FeOs: An Open-Source Framework for Equations of State and Classical Density Functional Theory".
But it's behind a paywall I hve no access to.
Could you perhaps post an author-copy?
But maybe I'm jumping the gun?
No offence, but it seems a contradiction in terms to have a paper on Open Source that is not itself Open source....:}
I tried SciHub and LibraryGenesis but no luck.
parameters = PcSaftParameters.from_json(
['toluene', 'acetone'],
'../parameters/pcsaft/loetgeringlin2018.json'
)
pcsaft = HelmholtzEnergyFunctional.pcsaft(parameters)
vle = PhaseDiagram.binary_vle(pcsaft, 300 * KELVIN, 251)
gamma = [PlanarInterface.from_tanh(pe, 1024, 100 * ANGSTROM, 500 * KELVIN).solve().surface_tension() for pe in vle.states]
results in RuntimeError: The matrix appears to be singular.
for both end-points (pure substances) of the phase diagram.
The above functionality can be done with a SurfaceTensionDiagram
but would it be helpful to handle PhaseEquilibrium
inputs for mixtures with x=1
?
The implementation of the PeTS and UV equations of state might be simplified by reusing the implementation of the BMCSL equation of state that is used in the SAFT models.
Signature:
State.critical_point_binary(
eos,
temperature_or_pressure,
#initial_temperature=None, # this line is missing
initial_molefracs=None,
max_iter=None,
tol=None,
verbosity=None,
)
Docstring:
Create a thermodynamic state at critical conditions for a binary system.
Parameters
----------
eos: EquationOfState
The equation of state to use.
temperature_or_pressure: SINumber
temperature_or_pressure.
initial_temperature: SINumber, optional
An initial guess for the temperature.
initial_molefracs: [float], optional
An initial guess for the composition.
max_iter : int, optional
The maximum number of iterations.
tol: float, optional
The solution tolerance.
verbosity : Verbosity, optional
The verbosity.
Returns
-------
State : State at critical conditions.
Type: builtin_function_or_method
api/model.md
EquationOfState.UVTheory
:
parameters
and wrong docstringPerturbation
feos.uvtheory.Perturbation
: missing docstringfeos.uvtheory.UVParameters
: "binary saft parameter records"feos.uvtheory.UVRecord
: describe attributes and/or default constructor.Feel free to add more. I'd favor more separate notebooks with focused scope - makes it easier for user to find what they look for.
In implementing teqp (https://github.com/usnistgov/teqp), I found that automatic differentiation was MUCH faster than complex step derivatives and multicomplex numbers. As you wrote the library in Rust, have you benchmarked your hyper dual derivatives with autodiff? I used this package in C++: https://github.com/autodiff/autodiff. I think you could also use this in Rust as Rust is C++-derived?
Example in Python (as in lj_models.ipynb):
sigma = 3.7039
eps_k = 150.03
parameters = UVParameters.new_simple(12.0, 6.0, sigma, eps_k)
uvtheory_bh = EquationOfState.uvtheory(parameters, perturbation=Perturbation.BarkerHenderson)
uvtheory_bh.third_virial_coefficient(6 * KELVIN)
returns NaN m³/mol²
Works for uv-B3 & uv-WCA implementation.
Is there a tutorial on how to use the estimator tool from python? I couldn't seem to find one, but I might be missing something.
Contributions.IdealGas
uses different methods for EoS and DFT (see below).
Joback gives very small values for the IdealGas
molar enthalpy (as fat as I tested all in the range ~1e-13 * JOULE).
import numpy as np
from feos.si import *
from feos.pcsaft import *
from feos.eos import EquationOfState, Contributions
from feos.eos import State as EosState
from feos.eos import PhaseEquilibrium as EosPhaseEquilibrium
from feos.dft import HelmholtzEnergyFunctional, PhaseEquilibrium
from feos.dft import State as DftState
from feos.dft import PhaseEquilibrium as DftPhaseEquilibrium
substances = ['nitrogen', 'methane']
params = PcSaftParameters.from_json(substances=substances, pure_path='pure_parameters.json', binary_path='binary_parameters.json', search_option=IdentifierOption.Name)
eos = EquationOfState.pcsaft(params)
dft = HelmholtzEnergyFunctional.pcsaft(params)
vle_eos = EosPhaseEquilibrium.bubble_point(eos, temperature_or_pressure=110*KELVIN, liquid_molefracs=np.array([0.1, 0.9]))
vle_dft = DftPhaseEquilibrium.bubble_point(dft, temperature_or_pressure=110*KELVIN, liquid_molefracs=np.array([0.1, 0.9]))
print(vle_eos.liquid.helmholtz_energy_contributions()) # Gives QSPR as IdealGas contribution
print(vle_dft.liquid.helmholtz_energy_contributions()) # Gives Joback as IdealGas contribution
print(vle_eos.liquid.molar_enthalpy(contributions=Contributions.ResidualNvt) - vle_dft.liquid.molar_enthalpy(contributions=Contributions.ResidualNvt)) #Gives very good agreement in the ResidualNvt contribution
print(vle_eos.liquid.molar_enthalpy(contributions=Contributions.IdealGas) - vle_dft.liquid.molar_enthalpy(contributions=Contributions.IdealGas)) # Gives large discrepancy in IdealGas contribution
Some recent and some not so recent publications show the advantage of incorporating association contributions for binary mixtures in which both pure components are not self-associating. Conceptually this is straightforward to implement in any SAFT model. The question is, how the additional parameters can be specified, especially because they have no effect on pure component properties.
The prediction of a target property for a given model and a set of thermodynamic states is a problem that can easily be parallelized.
Our current DataSet
trait's predict
method is very flexible in that a user can freely decide how to iterate over data and possibly calculate properties that are needed during that iteration. The downside of the current design is that we cannot implement the parallelization in a generic way.
This issue discusses ways to change the DataSet
trait so that a generic parallel evaluation of data points can be provided.
We could add a method into the trait that returns the prediction for a single data point.
// in trait DataSet
fn predict_datapoint(&self, eos: &Arc<E>, input: SINumber) -> Result<SINumber, EstimatorError>;
The prediction method for all data can then loop over this method. The same method could be reused for a parallel and a sequential prediction method.
However, different properties require different inputs both in terms of the number of inputs as well as the data type(s). E.g.
SINumber
SINumber
f64
, t, p as SINumber
SINumber
)The above predict_datapoint
method would work for the vapor pressure but not for the chemical potential.
prediction
method for a data pointWe could get rid of the unit in the in- and output and be generic in the length of in- and output data.
pub trait DataSet<E: EquationOfState>: Send + Sync {
/// This function is called prior to calculation of predictions.
///
/// Can be used to calculate an internal state needed for the predictions,
/// such as critical temperature or Antoine Parameters for vapor pressure
/// extrapolation.
fn prepare(&mut self, eos: &Arc<E>) -> Result<(), EstimatorError>;
/// Prediction of the target given the model and a single data point.
fn predict_datapoint(&self, eos: &Arc<E>, input: &[f64]) -> Vec<Result<f64, EstimatorError>>;
/// Return an iterator over input elements.
fn input(&self) -> &[Vec<f64>];
/// Prediction of the target given the model for all stored data points.
fn predict(&mut self, eos: &Arc<E>) -> Result<Vec<f64>, EstimatorError> {
self.prepare(eos)?;
self.input()
.par_iter()
.flat_map(|input| self.predict_datapoint(eos, input))
.collect()
}
}
relative_difference
(and thus the cost function) can be generically implemented since the result of predict is just a Vec<f64>
.DataSet
s can be stored in a Vec<Arc<dyn DataSet<E>>>
in the Estimator
which then can be used as is.predict
are always the same which is nice to check/plot how a model's parameters perform.Vec
s have to be allocated during the iteration (most of the time with a single value)DataSet
traitThe interface can be written in a nicer way using associated types and constants. However, the trait is no longer object safe. We'd have to build an enum with all possible implementors of DataSet
so that those can be used within an Estimator inside a Vec
.
pub trait DataSet<E: EquationOfState, const NTARGET: usize>: Send + Sync {
type Input: Send + Sync; // data type of input
type Target: Send + Sync; // data type of output
fn target(&self) -> &[Self::Target];
/// This function is called prior to calculation of predictions.
///
/// Can be used to calculate an internal state needed for the predictions,
/// such as critical temperature or Antoine Parameters for vapor pressure
/// extrapolation.
fn prepare(&mut self, eos: &Arc<E>) -> Result<(), EstimatorError>;
/// Prediction of the target given the model and a single data point.
fn predict_datapoint(
&self,
eos: &Arc<E>,
input: &Self::Input,
) -> Result<Self::Target, EstimatorError>;
/// Return an iterator over input elements.
fn input(&self) -> &[Self::Input];
/// Calculate relative difference
fn relative_difference_datapoint(
&self,
eos: &Arc<E>,
input: &Self::Input,
target: &Self::Target,
) -> Result<[f64; NTARGET], EstimatorError>;
/// Prediction of the target given the model for all stored data points.
fn predict(&mut self, eos: &Arc<E>) -> Result<Vec<Self::Target>, EstimatorError> {
self.prepare(eos)?;
self.input()
.par_iter()
.map(|input| self.predict_datapoint(eos, input))
.collect()
}
fn relative_difference(&mut self, eos: &Arc<E>) -> Result<Vec<f64>, EstimatorError> {
self.prepare(eos)?;
// can be done without collecting twice with par_extend?
let rel_dif = self
.input()
.par_iter()
.zip(self.target())
.map(|(input, target)| self.relative_difference_datapoint(eos, input, target))
.collect::<Result<Vec<[f64; NTARGET]>, EstimatorError>>()?;
Ok(rel_dif.par_iter().cloned().flatten().collect())
}
}
Estimator
.An implementation for the vapor pressure could look like this:
pub struct VaporPressure {
pub target: Vec<SINumber>,
temperature: Vec<SINumber>,
max_temperature: SINumber,
antoine: Option<Antoine>,
solver_options: SolverOptions,
}
impl VaporPressure {
/// Create a new data set for vapor pressure.
///
/// If the equation of state fails to compute the vapor pressure
/// (e.g. when it underestimates the critical point) the vapor
/// pressure can be estimated.
/// If `extrapolate` is `true`, the vapor pressure is estimated by
/// calculating the slope of ln(p) over 1/T.
/// If `extrapolate` is `false`, it is set to `NAN`.
pub fn new(
target: SIArray1,
temperature: SIArray1,
extrapolate: bool,
solver_options: Option<SolverOptions>,
) -> Result<Self, EstimatorError> {
let max_temperature = temperature
.to_reduced(KELVIN)?
.into_iter()
.reduce(|a, b| a.max(b))
.unwrap()
* KELVIN;
let antoine = if extrapolate {
Some(Antoine::default())
} else {
None
};
Ok(Self {
target: target.into_iter().collect(),
temperature: temperature.into_iter().collect(),
max_temperature,
antoine,
solver_options: solver_options.unwrap_or_default(),
})
}
}
impl<E: EquationOfState> DataSet<E, 1> for VaporPressure {
type Input = SINumber;
type Target = SINumber;
fn target(&self) -> &[Self::Target] {
&self.target
}
fn prepare(&mut self, eos: &Arc<E>) -> Result<(), EstimatorError> {
if self.antoine.is_some() {
let critical_point = State::critical_point(
eos,
None,
Some(self.max_temperature * KELVIN),
self.solver_options,
)?;
let tc = critical_point.temperature;
let pc = critical_point.pressure(Contributions::Total);
let t0 = 0.9 * tc;
let p0 = PhaseEquilibrium::pure(eos, t0, None, self.solver_options)?
.vapor()
.pressure(Contributions::Total);
self.antoine = Some(Antoine::new(pc, p0, tc, t0)?);
}
Ok(())
}
fn input(&self) -> &[Self::Input] {
&self.temperature
}
fn predict_datapoint(
&self,
eos: &Arc<E>,
input: &Self::Input,
) -> Result<Self::Target, EstimatorError> {
let vle = PhaseEquilibrium::pure(eos, *input, None, self.solver_options);
if let Ok(vle) = vle {
Ok(vle.vapor().pressure(Contributions::Total))
} else if let Some(antoine) = &self.antoine {
antoine.pressure(*input)
} else {
Ok(f64::NAN * PASCAL)
}
}
fn relative_difference_datapoint(
&self,
eos: &Arc<E>,
input: &Self::Input,
target: &Self::Target,
) -> Result<[f64; 1], EstimatorError> {
self.predict_datapoint(eos, input)
.and_then(|prediction| Ok([((target - prediction) / target).into_value()?]))
}
}
For more complex predictions, e.g. BinaryVleChemicalPotential
this could look like so:
pub struct BinaryVleChemicalPotential {
input: Vec<(f64, f64, SINumber, SINumber)>,
target: Vec<(SINumber, SINumber)>,
}
impl BinaryVleChemicalPotential {
pub fn new(
temperature: SIArray1,
pressure: SIArray1,
liquid_molefracs: Array1<f64>,
vapor_molefracs: Array1<f64>,
) -> Self {
let target: Vec<(SINumber, SINumber)> = (0..temperature.len())
.map(|_| (500.0 * JOULE / MOL, 500.0 * JOULE / MOL))
.collect();
let mut input = Vec::new();
for (((&xi, &yi), t), p) in liquid_molefracs
.iter()
.zip(vapor_molefracs.iter())
.zip(temperature.into_iter())
.zip(pressure.into_iter())
{
input.push((xi, yi, t, p));
}
assert_eq!(input.len(), target.len());
Self { input, target }
}
}
impl<E: EquationOfState> DataSet<E, 2> for BinaryVleChemicalPotential {
type Input = (f64, f64, SINumber, SINumber);
type Target = (SINumber, SINumber);
fn target(&self) -> &[Self::Target] {
&self.target
}
fn input(&self) -> &[Self::Input] {
&self.input
}
#[inline]
fn prepare(&mut self, eos: &Arc<E>) -> Result<(), EstimatorError> {
Ok(())
}
fn predict_datapoint(
&self,
eos: &Arc<E>,
input: &Self::Input,
) -> Result<Self::Target, EstimatorError> {
let xi = input.0;
let yi = input.1;
let t = input.2;
let p = input.3;
let liquid_moles = arr1(&[xi, 1.0 - xi]) * MOL;
let liquid = State::new_npt(eos, t, p, &liquid_moles, DensityInitialization::Liquid)?;
let mu_liquid = liquid.chemical_potential(Contributions::Total);
let vapor_moles = arr1(&[yi, 1.0 - yi]) * MOL;
let vapor = State::new_npt(eos, t, p, &vapor_moles, DensityInitialization::Vapor)?;
let mu_vapor = vapor.chemical_potential(Contributions::Total);
Ok((
mu_liquid.get(0) - mu_vapor.get(0) + 500.0 * JOULE / MOL,
mu_liquid.get(1) - mu_vapor.get(1) + 500.0 * JOULE / MOL,
))
}
fn relative_difference_datapoint(
&self,
eos: &Arc<E>,
input: &Self::Input,
target: &Self::Target,
) -> Result<[f64; 2], EstimatorError> {
self.predict_datapoint(eos, input).and_then(|prediction| {
Ok([
((target.0 - prediction.0) / target.0).into_value()?,
((target.1 - prediction.1) / target.1).into_value()?,
])
})
}
}
predict
leaving the implementation to the userDataSet
traitI would like to experiment with the very exciting uv-theory stuff in my code, and I can call that from Python, but to integrate with the tools I am developing, I need a C/C++ interface. Is it possible to develop such an interface easily with rust?
Hello,
I would like to fit other cubic EoS to experimental data using FeOs. For this I have used as a starting point core_user_define_eos.ipynb and binary_parameter_optimization.ipynb. This works fine for PC-SAFT, but reading multiple *.json files including binary parameters for a general EoS is causing an error which I do not understand. Do you have any insights? I am working with the Peng-Robinson example to start. Please refer to the attachment and the following section of code.
parameters = PengRobinsonParameters.from_multiple_json(
[
(['argon'], file_pure),
(['ammonia'], file_pure)
],
binary_path=file_binary,
)
parameters
RuntimeError Traceback (most recent call last)
~\AppData\Local\Temp\ipykernel_3844\3446048090.py in
----> 1 parameters = PengRobinsonParameters.from_multiple_json(
2 [
3 (['argon'], file_pure),
4 (['ammonia'], file_pure)
5 ],
RuntimeError: invalid type: map, expected f64 at line 19 column 25
For the python
equation of state, users can define their own helmholtz_energy
function that takes a StateHD
object as input. In the function, properties of the state can be accessed, e.g. one can write state.moles
.
To make this work, there has to be a non-generic state object for each (hyper) dual number.
Currently, missing dual numbers are simply defined in feos-core
. Using these definitions, for each a non-generic StateHD
version is built.
There are currently two issues:
num-dual
(which currently does not export all variants we need to Python)impl_state_hd!
(which implement the getters) for all states that are built. Hence, there will be errors in Python when one tries to call the getters.To fix this, we
num-dual
. (Check class names in macros!)HelmholtzEnergyDual
in single macro?c1 = PureRecord(Identifier(), 1.0, PcSaftRecord(1, 3.0, 150.0))
c2 = PureRecord(Identifier(), 1.0, PcSaftRecord(1, 3.0, 150.0))
func = HelmholtzEnergyFunctional.pcsaft(PcSaftParameters.from_records([c1, c2]))
can not be run due to a missing argument. Passing an empty list results in an unwrap
error.
Currently an initial value for the temperature is required when calculating bubble or dew points at given pressure. This is in contrast to the calculations at given temperature for which robust estimations of starting values for the pressure are available.
If some application requires bubble or dew points at a given pressure without any knowledge about the temperature of the system, heuristics need to be implemented.
We should add __version__
to the package. I.e. add this to lib.rs
m.add("__version__", env!("CARGO_PKG_VERSION"))?;
When using PC-SAFT it is somewhat unclear which ideal gas model is used (see, e.g., #68). Should the selection be more explicit? Some thoughts:
Then there is also the issue with models implemented in Python:
I want to include a theory guide with the documentation of FeOs. The scope should be clearly separated from the user and developer guides that are already part of the documentation. That means, it is supposed to focus on the theory underlying the code and not on implementation details. Basically, it is supposed to outline which equations the code aims to solve and which models are included.
The following topics could at some point be part of the guide:
EOS
DFT
models
If you would like to contribute to any of these or other topics, leave a comment below or open a pull request :)
Cannot run this notebook because of above error pcsaft_phase_diagram.ipynb
The Important objects from FeOs
section mentions that Contributions
can be imported from the pcsaft
module but they are defined in the feos.eos
module.
At the moment, we calculate all properties of a State
that use second derivatives via HyperDual64
. Second derivatives w.r.t a single property, i.e. non-mixed derivatives, can be calculated using Dual2_64
which are a bit more efficient.
Should we add Dual2_64
to the PartialDerivative
enum and to the cache? E.g. we could do
// in state/mod.rs
#[derive(Clone, Copy, Eq, Hash, PartialEq, Debug)]
pub(crate) enum PartialDerivative {
Zeroth,
First(Derivative),
Second(Derivative),
SecondMixed(Derivative, Derivative),
Third(Derivative),
}
/// Creates a [StateHD] taking the first and second (non-mixed) derivatives.
pub fn derive2(&self, derivative: Derivative) -> StateHD<Dual2_64> {
let mut t = Dual2_64::from(self.reduced_temperature);
let mut v = Dual2_64::from(self.reduced_volume);
let mut n = self.reduced_moles.mapv(Dual2_64::from);
match derivative {
Derivative::DT => t = t.derive(),
Derivative::DV => v = v.derive(),
Derivative::DN(i) => n[i] = n[i].derive(),
}
StateHD::new(t, v, n)
}
/// Creates a [StateHD] taking the first and second mixed partial derivatives.
pub fn derive2_mixed(
&self,
derivative1: Derivative,
derivative2: Derivative,
) -> StateHD<HyperDual64> {
let mut t = HyperDual64::from(self.reduced_temperature);
let mut v = HyperDual64::from(self.reduced_volume);
let mut n = self.reduced_moles.mapv(HyperDual64::from);
match derivative1 {
Derivative::DT => t.eps1[0] = 1.0,
Derivative::DV => v.eps1[0] = 1.0,
Derivative::DN(i) => n[i].eps1[0] = 1.0,
}
match derivative2 {
Derivative::DT => t.eps2[0] = 1.0,
Derivative::DV => v.eps2[0] = 1.0,
Derivative::DN(i) => n[i].eps2[0] = 1.0,
}
StateHD::new(t, v, n)
}
// in state/cache.rs
pub fn get_or_insert_with_d2_64<F: FnOnce() -> Dual2_64>(
&mut self,
derivative: Derivative,
f: F,
) -> f64 {
if let Some(&value) = self.map.get(&PartialDerivative::Second(derivative)) {
self.hit += 1;
value
} else {
self.miss += 1;
let value = f();
self.map.insert(PartialDerivative::Zeroth, value.re);
self.map
.insert(PartialDerivative::First(derivative), value.v1[0]);
self.map
.insert(PartialDerivative::Second(derivative), value.v2[0]);
// also fill PartialDerivtave::SecondMixed(derivative, derivative)?
value.v2[0]
}
}
// in state/properties.rs
fn dp_dv_(&self, evaluate: Evaluate) -> QuantityScalar<U> {
-self.get_or_compute_derivative(PartialDerivative::Second(DV), evaluate)
}
fn dp_dt_(&self, evaluate: Evaluate) -> QuantityScalar<U> {
-self.get_or_compute_derivative(PartialDerivative::SecondMixed(DV, DT), evaluate)
}
Background: This will speed up algorithms that use those non-mixed, second derivatives, e.g. the density iteration. First implementation shows speedup of ~9 % for density iteration and 6 % for tp_flash
.
hi,
I was reading and trying the first example 'core_dual_numbers'
and got confused with some aspects:
(some of which apply to the example "core_user_defined_eos.ipynb as well")
see attachment notebook examples.zip
in the rev1 attachment i highlight some points of confusion
in the rev2 attachment i try to refactor the Helmholtz function of the EOS to S.I. and Reid/Poling/Prausnitz notation, and try to get the same results as before for the dimensionless results (a_kt)
main issues:
see values in the attachment
see values in the attachment
suggestions:
please see suggestion of macroscopic values
please see suggestion of my attempt at an eos reprogrammed in S.I. and with notation from reid/poling/prausnitz
where a has R**2 instead of R and helmholtz uses a term like a/(brt) instead of a/(bt)
thanks for your attention
The main example in the README doesn't work:
from feos.eos import EquationOfState, State
from feos.pcsaft import PcSaftParameters
# Build an equation of state
parameters = PcSaftParameters.from_json(['methanol'], 'parameters.json')
eos = EquationOfState.pcsaft(parameters)
# Define thermodynamic conditions
critical_point = State.critical_point(eos)
# Compute properties
p = critical_point.pressure()
t = critical_point.temperature
print(f'Critical point for methanol: T={t}, p={p}.')
I think because the path to "parameters.json"
is invalid. Looking into the wheel, it looks like the parameter files are not provided with the wheel. Could you please include them with the wheel?
Currently, the unit of the predicted property is "inferred" by taking the unit of the 0'th element of the target
vector. This panics if the vector is empty. See here.
In predict
, instead of allocating an array and iterating over the index, we can use iter().map().collect()
.
The workflow used to publish workspace crates seems to be not working currently. For the main feos crate https://github.com/actions-rs/cargo should work but apparently the repository is not being actively maintained any more.
A possible (much simpler) option would be https://github.com/dtolnay/rust-toolchain
Dear doctor:
I am trying to write a python program for copolymer PC-SAFT equation of state.
In the article "Perturbed-Chain SAFT: An Equation of State Based on a Perturbation Theory for Chain Molecules", Professor Gross gave all expression of residual Helmholtz energy, density, compressibility factor, fugacity coefficient, residual enthalpy and entropy of homopolymer system.
In the other article "Modeling Copolymer Systems Using the Perturbed-Chain SAFT Equation of State", he gave expressions of residual Helmholtz energy of comopolymer system, but did not provide expressions of other physical quantities.
Can you provide expressions or codes of density, compressibility factor, fugacity coefficient, residual enthalpy and entropy of copolymer system without derivative term? Thank you very much.
The SAFT-VRQ-Mie functional converges less robustly than PC-SAFT due to the calculation of local mole fractions. Due to the Gibbs phenomenon, it is almost unavoidable that the density within the pore wall becomes 0 at some point. In that case the calculation of local mole fractions generates NaN.
One remedy for pure components is to write a dedicated implementation of the functional specifically for pure components.
Other remedies would be to "clean" the values of the Helmholtz energy density in places where the (total) density is zero or rewrite the functional without calling the equation of state.
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