def edowham(alpha_p, e_eff):
    """

    Calculate the elasticity parameter of the contact problem according to
    Dowson-Hamrock.

    Parameters
    ----------
    alpha_p: ndarray, scalar
        The pressure-viscosity coefficient of the lubricant.
    e_eff: ndarray, scalar
        The effective modulus of the contact problem.

    Returns
    -------
    param_elasticity: ndarray, scalar
        The elasticity parameter of the contact problem.

    """
    param_elasticity = alpha_p * e_eff
    return param_elasticity