def theta_wtt(k, area, initial_volume):
    """
    Return the values of theta without the time [1/s]
    source: (Stiver and Mackay, 1984)

    Parameters
    ----------
    k : Mass transsfert coefficent [m/s]
    area : Area [m²]
    initial_volume : Initial spill volume [m³]

    """
    return (k * area) / initial_volume