120
B. J. Haupt· K. Stattegger . D. Seidov
The equation for dynamic viscosity 11
(6)
is approximated by a polynom (Matthaus 1972). The total vertical velocity of Wg
is the sum of the water velocity and the particle settling velocity:
Wg =w+ws.
(7)
At the surface, the "rigid-lid" approximation is used:
Wsurf = 0 for z = o.
(8)
The "rigid-lid" approximation eliminates external gravity waves and allows
for a longer time step (M) (Cox 1984; Haupt 1990; LeBlond and Mysak 1978). At
lateral boundaries "no-flux" and "no-slip" boundary conditions are used:
u,v,C n =0.
(9)
No bottom friction is used, but rather a "free-slip" boundary condition is employed at the bottom:
au av =0
az' az .
The fluxes through the bottom and lateral boundaries are set to zero:
aT, as , ac = o.
an an an
(10)
(11)
The vertical velocity W at the bottom is calculated using the continuity equation
W=_(u aH +vaH).
ax ay
(12)
2.6
The Two-Dimensional Sub model of SEDLOB
In many aspects, the 2-D submodel of SEDLOB is similar to the 3-D submodel.
The sediment transport at the bottom has the form
(13)
The submodel uses the same hydrostatic equation for the local pressure p [ef.
Eq. (3)], the same set of nonlinear equations for density [ef. Eq. (4)] and viscos-