In this equation we have mixed the dispersion part with the diffusion, so to say, by introducing a total viscosity. However, this way does not provide a pure turbulence modelling anymore, independent from the turbulence model used, since this integrated approach also models the dispersion.

In Eq. 2-198 and Eq. 2-199 all fields are time- and depth-averaged. Bars across, waves or other means of symbol declaration for the time- and depth-averaging have been left away and will not be used in the following chapters either.