The values of the dimensional constants Cj, C2, and C3 in Equations
3-74, 3-75 and 3-76 dépend on the units used in performing the calculations
Table 3-9 gives the dimensions of the variables used in the numerical
scheme in three Systems of units and the corresponding value of the
constants for each System. The first column of units is given in the
metric System while the other two are given in mixed units in the English
System.
Table 3-9. Systems of Units for Storm Surge Computations
Parameters
Units and Constant Values
Metric
Mixed English
△x
km
nm
mi
△S-, AS,.
•** *7
m
ft
ft
g
m/sec2
ft/sec2
ft/sec2
D
m
ft
ft
A, B
(km/hr)2
(nm/hr)2
(mi/hr)2
V
km2/hr
nm2/hr
mi2/hr
f
hr"1
hr-1
hr-1
△ t
hr
hr
hr
Cl
3.94
269
176
c2
2.06
141
92
C3
(1000)2
(6080)2
(5280) 2
The assumptions for this model are reasonably good only when the
momentum of the water is increasing under the influence of the wind,
•
when the right side of Equation 3-76 is positive. This condition can be
considered in the calculations by using the relation
(3-77)
For a dérivation of this équation see Bodine (1971). Should V at a
particular time level, as evaluated from Equation 3-76, be less than the
value obtained from Equation 3-77, then the resuit from Equation 3-77 is
ignored. However, if the opposite is true, then as an estimate, V is
taKen equal to the maximum possible value as given by Equation 3-77.
3-108