1458 
(b) The second condition is that the medium behind the 
reflected wave flows parallel to the boundary also: 
: , 
Wn Os Ue Ae @ (21) 
All investigations for this effect shall only concern low 
pressure ( W < 500 at). Then these two conditions can be com- 
bined with the relations (3), (4), and (5). If we designate 
(22) 
it will be “ound 
De a(lipr) 
VC Cece aa7 ; 
/ 
a7), = (tlio -hWig M7) 
aale ap Was os 
ul =akan'(' (Ark) 
Combination of (23) with (20) and (21) together with the 
f 
fact that @ and @ for that range are small, zives: 
,-2e) pa 
/+( 2h - k)T+eean ‘Kr 0) (20a) 
/ 2 
7 ae ee cee 
(21a) 
7@ =~ 7TO'(l- (er+w7) 
(20a) can be transformed and finally gives: 
Ore 7) - 2 ied f- L deT- ke ao Q (24) 
50 
