Lumley 



© 



LpSSY 



DOWNSTREAM 



© 



MASSY GAINY 



BOUNDARY CONDITIONS FOR SEMI - INFINITE 

 LINEAR VISCO- ELASTIC SOLID 



PHASE RELATIONS 

 IN BOUNDARY LAYER OVER 

 RIGID SURFACE 



DOWN 

 STREAM 



|5 



n UPSTREAM 



MASSY 



BOUNDARY LAYER WITH 



FLEXIBLE WALL 

 SPRINGY/GOOD MASSY/BAD 

 LOSSY /BAD GAINY/GOOD 



LATERAL RESPONSE BAD 



Fig. 6 - Small disturbance phase relations in a vis- 

 cous region near the wall: first-order modification 

 by flexible wall. 



surface (Miller) & Fejer (1964)).* Detailed, qualitative experimental data on any 

 technique is relatively sparse, as sparse, say, as equally detailed theory. Prob- 

 ably most is known about and greatest success has been achieved with suction 

 through slots and the Toms phenomenon. The mechanism of the former is clear, 

 though the mechanism of the latter is far from being so. If another speculation 

 may be added to a growing list, it seems quite possible that we may learn more 

 about the ordinary turbulent boundary layer by examining the effects of various 

 changes; it is at least clear that there are interesting areas here for investiga- 

 tion. 



'=Nor have we discussed blowing, and other means of artifically thickening the 

 turbulent boundary layer, since it does not seem obvious that one can recover 

 the work done to thicken the layer. 



928 



