1526 
tends to zero when O€—>O , as would be expected. 
8.6 In order to use the above results to predict rise times 
and wave shapes for actual cases of interest, one must be able 
to estimate the value of a and consequently o . For this pur- 
pose we use the attenuation coefficients for sea water reported 
by Liebermann? ®; 
A w* 
oy = ——————— r Be 
feraus o> (94) 
where A= 29x 10719 sec/cm 
Bs 1.2x 10717  sec®/cm 
Cedex 10-6 SEC. 
(Liebermann uses o to denote the attenuation coefficient, and 
we replace it by XY to prevent confusion in notation.) ° 
Instead of simply relying upon classical values of 
shear viscosity to calculate a from equation (79), we adopt 
Liebermann's results, which include the effects of dilational 
viscosity as well as shear, and evaluate a on the basis that 
aie 2 
Os p/w (95) 
A rigorous evaluation, using equation (94) for We 
would be extremely difficult because of the manner in which it 
would complicate the integral in equation (78). In order to 
utilize the simplified results already obtained, we neglect the 
relaxation effect indicated in (94) and approximate by setting: 
(Oe AbG+B yp 
Z (96) 
