Physical Oceanography, Vol.
A MODEL OF THE BOTTOM TURBULENT LAYER
IN THE SHALLOW-WATER REGION
V. Z . D y k m a n ,
O. I. Efremov,
and V. A. Ivanov
We present a semiempirical model of the bottom turbulent boundary layer aimed at the application as
one of the components of the procedure of evaluation of the vertical distribution of the concentration of
suspensions in the coastal region of the sea. The model is based on data of laboratory experiments and is
suitable for the sand bottom in a broad range of amplitudes of the bottom velocities of the wave origin.
The processes of accumulation of sediments run for millions of years. To a significant extent, they formed
the current shape of Earth’s surface and, hence, deserve a detailed description, as exact as possible. The kinetic
approach to the description of motion of suspensions is based on the use of certain ideas concerning the detailed
structure of the analyzed processes. Thus, it is necessary to consider the probability distribution functions of
solid and liquid particles and analyze the frequency and space spectra of the wave and turbulent motions. The
kinetic models are more complicated than the hydrodynamic models but enable one to better understand the
physical nature of the phenomena.
For many years, the problems of physical modeling of various characteristics of the field of suspensions in
the coastal region of the sea are studied at the Marine Hydrophysical Institute of the Ukrainian Academy of Sci-
ences on the basis of the kinetic ideas . The developed model combines the constructed probability distribu-
tion functions of suspended particles, the kinetic model of the intensity of wind-induced waves, and the spectral
model of the subsurface turbulence generated by waves.
As one of the main problems, we can mention the investigation of regularities of the transport of sand sedi-
ments under the action of waves in the surf zone. In passing to the shallow-water region, the long-wave part of the
packet of wind waves is subjected to rapid transformations, and the pulsed horizontal wave motions generate bot-
tom turbulence directly near the bottom. Note that its characteristics strongly differ from the characteristics of the
The initial roiling of sediments occurs with direct participation of the bottom turbulence which, in fact,
forms the field of suspension at a distance of several first centimeters from the bottom and, hence, plays the role
of the most important component of the kinetic models of motion of the sediments. The bottom turbulence lies
within the sphere of action of the theory of boundary layer near the solid wall but contains numerous elements
which make the theoretical description of this phenomenon much more complicated. Among these elements, we
can mention the pulsed character of motion and the diverse types of roughness of the bottom. In view of these
circumstances, the problem of modeling of the bottom turbulence is, to a large extent, based on the empirical
data and, in particular, on the results of laboratory experiments.
Marine Hydrophysical Institute, Ukrainian National Academy of Sciences, Sevastopol, Ukraine.
Corresponding author; e-mail: firstname.lastname@example.org.
Translated from Morskoi Gidrofizicheskii Zhurnal, No.
49–62, March–April, 2010. Original article submitted November 18, 2008;
revision submitted January 20, 2009.
122 0928–5105/10/2002–0122 © 2010 Springer Science+Business Media, Inc.