flowtube.viscosity_density
==========================

.. py:module:: flowtube.viscosity_density

.. autoapi-nested-parse::

   Handles the calculation of the viscosity and density of a variety of
   pure gases.

   Citations
       “A8: Van Der Waal’s Constants for Real Gases.” Chemistry LibreTexts,
       November 14, 2024. Accessed August 6, 2025.
       https://chem.libretexts.org/Ancillary_Materials/Reference/Reference_Tables/Atomic_and_Molecular_Properties/A8%3A_van_der_Waal’s_Constants_for_Real_Gases.

       “NIST Chemistry Webbook, SRD 69.” Thermophysical Properties of Fluid
       Systems. Accessed August 6, 2025.
       https://webbook.nist.gov/chemistry/fluid/.

       Reid, R.C., Prausnitz, J.M., Poling, B.E., 1987. The Properties of
       Gases and Liquids, 4th ed. McGraw-Hill, New York.



Attributes
----------

.. autoapisummary::

   flowtube.viscosity_density.a
   flowtube.viscosity_density.b
   flowtube.viscosity_density.T_c
   flowtube.viscosity_density.P_c
   flowtube.viscosity_density.mu


Classes
-------

.. autoapisummary::

   flowtube.viscosity_density.basic_attrs


Functions
---------

.. autoapisummary::

   flowtube.viscosity_density.real_density
   flowtube.viscosity_density.dynamic_viscosity


Module Contents
---------------

.. py:class:: basic_attrs

   Bases: :py:obj:`Protocol`


   Base class for protocol classes.

   Protocol classes are defined as::

       class Proto(Protocol):
           def meth(self) -> int:
               ...

   Such classes are primarily used with static type checkers that recognize
   structural subtyping (static duck-typing).

   For example::

       class C:
           def meth(self) -> int:
               return 0

       def func(x: Proto) -> int:
           return x.meth()

       func(C())  # Passes static type check

   See PEP 544 for details. Protocol classes decorated with
   @typing.runtime_checkable act as simple-minded runtime protocols that check
   only the presence of given attributes, ignoring their type signatures.
   Protocol classes can be generic, they are defined as::

       class GenProto[T](Protocol):
           def meth(self) -> T:
               ...


   .. py:attribute:: P
      :type:  float


   .. py:attribute:: T
      :type:  float


.. py:data:: a

.. py:data:: b

.. py:data:: T_c

.. py:data:: P_c

.. py:data:: mu

.. py:function:: real_density(obj: basic_attrs, gas: str) -> float

   Calculates the real density of a gas using van der Waal's equation
   of state.

   :param obj: Object with basic attributes
               (P in Pa, T in K).
   :type obj: basic_attrs
   :param gas: Molecular formula of gas (supported: Ar, He, N2, O2).
   :type gas: str

   :returns: Real density of gas in kg m-3.
   :rtype: float


.. py:function:: dynamic_viscosity(obj: basic_attrs, gas: str) -> float

   Estimate absolute/dynamic viscosity of pure gases using the
   corresponding states method from Reid et al., 1987.

   :param obj: Object with basic attributes
               (P in Pa, T in K).
   :type obj: basic_attrs
   :param gas: Molecular formula of gas (supported: Ar, He, N2, O2).
   :type gas: str

   :returns: Gas viscosity (kg m-1 s-1).
   :rtype: float