SADKAT-Extension/solution.py at main · Fraser-Crawford/SADKAT-Extension · GitHub

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from dataclasses import dataclass
from collections.abc import Callable
import numpy as np
import numpy.typing as npt
from solvent import Solvent


@dataclass
class Solution:
    """Class to conveniently store all parameters needed to describe a solute together."""

    solvent: Solvent
    molar_mass_solute: float  # g/mol
    num_ions: int  # unitless
    solubility_limit: float  # kg per kg solvent
    solid_density: float  # kg/m^3
    density: Callable[[float|npt.NDArray[np.float_]],float|npt.NDArray[np.float_]]  # kg/m^3
      # a fitting function for solvent activity (unitless) in
    # terms of the mass fraction of solute, or None (the
    # default) to assume Raoult's law for ideal mixtures
    activity: Callable[[float | npt.NDArray[np.float_]], float | npt.NDArray[np.float_]]
    solid_refractive_index: float
    concentration_coefficients = None
    density_derivative_coefficients = None

    def mole_fraction_solute(self, mass_fraction_solute):
        """Mole fraction from mass fraction."""
        w_solute = mass_fraction_solute / self.molar_mass_solute
        w_solvent = (1 - mass_fraction_solute) / self.solvent.molar_mass
        return w_solute / (w_solute + w_solvent)

    def mole_fraction_solvent(self, mass_fraction_solute):
        """Mole fraction of *solvent* from mass fraction of *solute*."""
        return 1 - self.mole_fraction_solute(mass_fraction_solute)

    def concentration_to_solute_mass_fraction(self, concentration):
        if self.concentration_coefficients is None:
            mfs = np.linspace(0,1.0,100)
            concentrations = mfs*self.density(mfs)
            self.concentration_coefficients = np.polyfit(concentrations, mfs, 6)
        return np.poly1d(self.concentration_coefficients)(concentration)

    def concentration(self, mfs):
        return mfs * self.density(mfs)

    def density_derivative(self, mfs):
        if self.density_derivative_coefficients is None:
            mfs = np.linspace(0,1.0,100)
            densities = self.density(mfs)
            density_gradients = np.gradient(densities,mfs)
            self.density_derivative_coefficients = np.polyfit(mfs, density_gradients, 4)
        return np.poly1d(self.density_derivative_coefficients)(mfs)

    def mass_fraction_from_activity(self, activity):
        mfs = np.linspace(1.0, 0.0, 100)
        mfs_activity = self.activity(mfs)
        return np.interp(activity, mfs_activity, mfs)

    def refractive_index(self, mfs, temperature) -> float:
        """Returns the refractive index of the droplet based on a mass fraction/density correction."""
        solutionD = self.density(mfs)
        soluteD = self.solid_density
        soluteRI = self.solid_refractive_index
        solventD = self.solvent.density(temperature)
        solventRI = self.solvent.refractive_index
        return np.sqrt((1 + 2 * solutionD * (((soluteRI ** 2 - 1) * mfs) / ((soluteRI ** 2 + 2) * soluteD) + (
                (1 - mfs) * (solventRI ** 2 - 1)) / (solventD * (solventRI ** 2 + 2)))) / (1 - solutionD * (
                ((soluteRI ** 2 - 1) * mfs) / ((soluteRI ** 2 + 2) * soluteD) + (
                (1 - mfs) * (solventRI ** 2 - 1)) / (solventD * (solventRI ** 2 + 2)))))