1560 
14. 
Slope of the peak pressure similarity curve. 
14.1 We can use a method very similar to that of section 13 in 
order to estimate the peak attenuation due to viscous effects. 
Conbining equations (89) and (92), the relative peak pressure is 
given by 
Ob 
pn)e ele) | exp Cy) ey , 
£14 
- @-- U/2 ; 
Then, as in section 13, we differentiate equation (143) with 
respect to X and account for the sharpening effect by setting 
the resulting expression equal to Ap & o/aR and obtaining x 
as a function of R from Figure 10. The result of differentiation, 
making use of equations (92) and (97), is 
A). exp [a* ee +P: eek Ie [auraess( 4) 
exp |-(6.- -4)/4] Cs 0.328 (144) 
ve tga 
a. 
In these calculations ™ si Ip - 4), andl + pi [C= 2 | 
is always very nearly equal to 2- Therefore equation (144) may 
be somewhat simplified: 
a pG,) ~ _ x exp/-~(3,--4)| ey cars 
2 Aen! APE [. 
AR ic eae 5 
“peas a 74] (nee 2. gee ) (145) 
Numerical integration oe equation (145) was carried out for two 
charge sizes: 0.5 and 300 lb. over the wi/3/R interval 0.0053 
to 0.00022. The resulting relative pressures were plotted against 
_ Bh - 
