A, 13 -THEORIES BASED ON LOCAL PARAMETERS 



Schlichting's approach suggests the investigation of a procedure in 

 which the critical Reynolds number is taken not from stability calcu- 

 lations but from experimental values determined under simplified con- 

 ditions. Let us suppose that {Re^*)^^ could be determined from available 

 experimental data as a function of air stream turbulence, local pressure 

 gradient, and local surface roughness. We could then carry out a modified 



1.0 



(l-)cr 



0.8 



0.6 



0.4 



0.2 



10^ 



I 05 



5 10^ 2 



Uc/v 



10^ 



108 



Fig. A,12h. Location on elliptic cylinder at which boundary layer oscillations 

 are amplified as function of cylinder Reynolds number. 



1.0 

 0.8 

 0.6 

 0.4 

 0.2 

 



(?)c. 



10^ 



IQs 



106 



Uc/v 



10' 



10^ 



Fig. A,12i. Location on Joukowsky I airfoil at which boundary layer oscillations 

 are amplified as function of airfoil Reynolds number. 



Schlichting computation with some hope of better agreement with experi- 

 mentally observed transition points. Unfortunately, sufficient experi- 

 mental data are not available, and a complete test of this type of theory 

 must await further research. 



A, 13. Adequacy of Transition Theories Based on Local Pa- 

 rameters. The key assumption in Schlichting's approach is that 

 transition is determined by the local values of mean speed distribution. 



(37) 



