A, 5 • SURFACE ROUGHNESS AND WAVINESS 



length of about 1 cm, according to a letter from Holstein. The roughness 

 height given did not include the paper thickness. It seems probable that 

 the front edge of the paper is the critical roughness rather than the dis- 

 tributed roughness. Fig. A,5k shows Re^, plotted against k/b* where k is 



0.8 



0.6 



o 



I 



o 



X0.4 



a: 



0.2 



0.2 



k/5; 



0.3 



0.4 



Fig. A,6k. Effect of distributed roughness on the transition Reynolds 

 number of a plate. Measurements of Holstein as reported. 



1.2 

 O 0-8 



X 



^^0.4 



0.2 0.4 0.6 



0.2 4- k 



6* 

 n 



0.8 



Fig. A,51. Effect of distributed roughness on the transition Reynolds number 

 of a plate. Measurements of Holstein with suggested correction. 



the nominal roughness height and 5* is the displacement thickness at the 

 beginning of the roughened portion. Fig. A, 51 shows a plot of the same 

 results on the assumption that the roughness height is the tabulated value 

 plus 0.2 mm. 



If Holstein's results are analyzed in terms of the Reynolds number 



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