T H E 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[SIXTH SERIES.] 



v — — 



OCTOBER 11)19. 



XLT. Stream-line Flow from a Disturbed Area. By Lt.-Col. 

 A. R. Richardson, D.S.O., Imperial College of Science, 

 S. Kensington, S. W* 



THIS note is an attempt to find solutions, defining flow 

 past a rigid boundary, distinct from those obtained on 

 the electrical and discontinuous stream-line hypotheses. 



To fix ideas, consider the case of a plate placed broadside 

 onto a stream. 



In order to represent experimental facts the solution 

 should : 



(i.) Make the velocity finite everywhere, and discontinuous 

 nowhere. 



(ii.) Give stream-line motion everywhere except behind 

 the plate where eddying motion occurs. 

 Photographs show that behind, and close to the plate, 

 the motion is stream-line in character. (Advisory 

 Committee for Aeronautics, Report 58, 1912.) 



(iii.) Give reasons for the periodic formation of approxi- 

 mately circular eddies. 



(iv.) Explain why the resistance alters with the shape of 

 the underbody of the plate and with the initial 

 conditions in the fluid behind it, and also why 

 the pressure changes sign on the underside of the 

 plate. 



The analysis shows that if condition (i.) is satisfied 



* Communicated by the Author. 

 Phil Mag. S. 6. Vol. 38. No. 226. Oct, 1919. 2 H 



