Finite Element Techniques for Fluid Flow

INVISCID FLUIDS 185

The essential difficulty is the choice of

s,

i.e. the decision as to how

many generalised coordinates one should take. The solution is

'exact' only when s = n (exact here refers to the solution of the

discretised equations).

5.4 HARMONIC RESPONSE OF COASTAL WATERS

We will now consider a special case of the wave equation. This is the

problem of predicting the harmonic response of coastal waters.

Mean water level

Figure 5.3 Harmonic response—shallow waters

Figure 5.3 defines the notation for this case. We take η(χιΧ

2

ή as

the elevation above sea level (hydrostatic position) and work with

vertically integrated flow measures