Fink and Naudascher 
DISCUSSION 
Paul Lieber 
Untverstty of Caltfornta 
Berkeley, Caltfornta 
How do you account physically for the superiority of the 
momentum similarity law as compared to the velocity similarity law, 
if I understood your statement ? 
REPLY TO DISCUSSION 
Leo Fink 
Untverstty of Karlsruhe 
Karlsruhe, Germany 
If you substitute the conventional hypothesis in the diffe- 
rential form of the boundary-layer equation, you obtain a contradic - 
tion, and if you substitute the new hypothesis into this equation, you 
will not find any incompatibilities. This is perhaps the explanation 
why this new hypothesis works better than the old one. One other rea- 
son you can put forward is that these types of flow are mainly govern- 
ed by the momentum equation because the momentum flux is a cons- 
tant in these cases. Therefore, if the momentum equation is not 
violated by any of your assumptions, you have described the flow bet- 
ter than if you used the conventional hypothesis. 
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