def ratio_area_clay_total(ConcClay, material, DiamTube, RatioHeightDiameter):
    """Return the surface area of clay normalized by total surface area.

    Total surface area is a combination of clay and reactor wall
    surface areas. This function is used to estimate how much coagulant
    actually goes to the clay.

    :param ConcClay: Concentration of clay in suspension
    :type ConcClay: float
    :param material: Type of clay in suspension, e.g. floc_model.Clay
    :type material: floc_model.Material
    :param DiamTube: Diameter of flocculator tube (assumes tube flocculator for calculation of reactor surface area)
    :type DiamTube: float
    :param RatioHeightDiameter: Dimensionless ratio describing ratio of clay height to clay diameter
    :type RatioHeightDiameter: float

    :return: The ratio of clay surface area to total available surface area (accounting for reactor walls)
    :rtype: float
    """
    return (1
            / (1
               + (2 * material.Diameter
                  / (3 * DiamTube * ratio_clay_sphere(RatioHeightDiameter)
                     * (ConcClay / material.Density)
                     )
                  )
               )
            )