4/98
SED2D-WES Version 4.3 Beta
The characteristic time, tc , is somewhat subjective. It should be the amount of time required for the
concentration in the flow field to change from C to Ceq . In the case of deposition, tc is related to fall velocity.
The following expression was adopted.
D
Cd
Vs
tc = larger of or
(12)
DT
where
tc = characteristic time
Cd = coefficient for deposition
D = flow depth
Vs = fall velocity of a sediment particle
DT = computation time interval
In the case of scour, there are no simple parameters to employ. The following expression is used.
D
Ce
u
or
t c = larger of
(13)
DT
where
Ce = coefficient for entrainment
V = flow speed
12
WORKING DRAFT
Previous Page
