def stagnation_energy(V):
    """Calculates the increase in enthalpy `dH` which is provided by a fluid's
    velocity `V`.

    .. math::
        \\Delta H = \\frac{V^2}{2}

    Parameters
    ----------
    V : float
        Velocity [m/s]

    Returns
    -------
    dH : float
        Incease in enthalpy [J/kg]

    Notes
    -----
    The units work out. This term is pretty small, but not trivial.

    Examples
    --------
    >>> stagnation_energy(125)
    7812.5

    References
    ----------
    .. [1] Cengel, Yunus, and John Cimbala. Fluid Mechanics: Fundamentals and
       Applications. Boston: McGraw Hill Higher Education, 2006.
    """
    return 0.5 * V * V
