def round_edge_open_mesh(alpha, subtype='diamond pattern wire', angle=0):
    r'''Returns the loss coefficient for a round edged open net/screen
    made of one of the following patterns, according to [1]_:

    'round bar screen':

    .. math::
        K = 0.95(1-\alpha) + 0.2(1-\alpha)^2

    'diamond pattern wire':

    .. math::
        K = 0.67(1-\alpha) + 1.3(1-\alpha)^2

    'knotted net':

    .. math::
        K = 0.70(1-\alpha) + 4.9(1-\alpha)^2

    'knotless net':

    .. math::
        K = 0.72(1-\alpha) + 2.1(1-\alpha)^2

    Parameters
    ----------
    alpha : float
        Fraction of net/screen open to flow [-]
    subtype : str
        One of 'round bar screen', 'diamond pattern wire', 'knotted net' or
        'knotless net'.
    angle : float, optional
        Angle of inclination, with 0 being straight and 90 being parallel to
        flow [degrees]

    Returns
    -------
    K : float
        Loss coefficient [-]

    Notes
    -----
    `alpha` should be between 0.85 and 1 for these correlations.
    Flow should be turbulent, with Re > 500.

    Examples
    --------
    >>> round_edge_open_mesh(0.96, angle=33.)
    0.02031327712601458

    References
    ----------
    .. [1] Blevins, Robert D. Applied Fluid Dynamics Handbook. New York, N.Y.:
       Van Nostrand Reinhold Co., 1984.
    '''
    if subtype == 'round bar screen':
        K = 0.95*(1-alpha) + 0.2*(1-alpha)**2
    elif subtype == 'diamond pattern wire':
        K = 0.67*(1-alpha) + 1.3*(1-alpha)**2
    elif subtype == 'knotted net':
        K = 0.70*(1-alpha) + 4.9*(1-alpha)**2
    elif subtype == 'knotless net':
        K = 0.72*(1-alpha) + 2.1*(1-alpha)**2
    else:
        raise Exception('Subtype not recognized')
    if angle:
        if angle < 45:
            K *= cos(radians(angle))**2
        else:
            K *= interp(angle, round_thetas, round_gammas)
    return K