def Archimedes(L, rhof, rhop, mu, g=g):
    r'''Calculates Archimedes number, `Ar`, for a fluid and particle with the
    given densities, characteristic length, viscosity, and gravity
    (usually diameter of particle).

    .. math::
        Ar = \frac{L^3 \rho_f(\rho_p-\rho_f)g}{\mu^2}

    Parameters
    ----------
    L : float
        Characteristic length, typically particle diameter [m]
    rhof : float
        Density of fluid, [kg/m^3]
    rhop : float
        Density of particle, [kg/m^3]
    mu : float
        Viscosity of fluid, [N/m]
    g : float, optional
        Acceleration due to gravity, [m/s^2]

    Returns
    -------
    Ar : float
        Archimedes number []

    Notes
    -----
    Used in fluid-particle interaction calculations.

    .. math::
        Ar = \frac{\text{Gravitational force}}{\text{Viscous force}}

    Examples
    --------
    >>> Archimedes(0.002, 2., 3000, 1E-3)
    470.4053872

    References
    ----------
    .. [1] Green, Don, and Robert Perry. Perry's Chemical Engineers' Handbook,
       Eighth Edition. McGraw-Hill Professional, 2007.
    .. [2] Cengel, Yunus, and John Cimbala. Fluid Mechanics: Fundamentals and
       Applications. Boston: McGraw Hill Higher Education, 2006.
    '''
    return L**3*rhof*(rhop-rhof)*g/mu**2
r'''Calculates Archimedes number, `Ar`, for a fluid and particle with the
    given densities, characteristic length, viscosity, and gravity
    (usually diameter of particle).

    .. math::
        Ar = \frac{L^3 \rho_f(\rho_p-\rho_f)g}{\mu^2}

    Parameters
    ----------
    L : float
        Characteristic length, typically particle diameter [m]
    rhof : float
        Density of fluid, [kg/m^3]
    rhop : float
        Density of particle, [kg/m^3]
    mu : float
        Viscosity of fluid, [N/m]
    g : float, optional
        Acceleration due to gravity, [m/s^2]

    Returns
    -------
    Ar : float
        Archimedes number []

    Notes
    -----
    Used in fluid-particle interaction calculations.

    .. math::
        Ar = \frac{\text{Gravitational force}}{\text{Viscous force}}

    Examples
    --------
    >>> Archimedes(0.002, 2., 3000, 1E-3)
    470.4053872

    References
    ----------
    .. [1] Green, Don, and Robert Perry. Perry's Chemical Engineers' Handbook,
       Eighth Edition. McGraw-Hill Professional, 2007.
    .. [2] Cengel, Yunus, and John Cimbala. Fluid Mechanics: Fundamentals and
       Applications. Boston: McGraw Hill Higher Education, 2006.