Additives Injected Into the Boundary Layer of an Underwater Body 



The drag data on spheres from 0.25 inch to 2 inches in diameter showed 

 that Polyox reduced drag in all cases. The amount of drag reduction increased 

 with sphere diameter up to a maximum of 69 percent. The results on the stable 

 cones showed little or no drag reduction or change in wake shape due to the 

 Polyox additive. In the tests on the unstable bodies that were tested, such as 

 cylinders and the flatter cones, the Polyox had a small effect on stabilizing the 

 trajectories. 



REPLY TO THE DISCUSSION 



W. M. Vogel and A. M. Patterson 

 Pacific Naval Laboratory 

 Victoria, B. C. 



The discussion by Dr. Eringen* on his theory of simple micro-fluids was very 

 interesting. We have not had time to assimilate the material presented in his 

 referenced report, but if this theory can be used to predict the behaviour of di- 

 lute polymer solutions it will be a major step in our understanding of these fluids. 



With reference to Mr. Lang's comments we have carried out some experi- 

 ments with a cylinder mounted across our water tunnel. We have not measured 

 the drag but when dilute polymer solutions are injected from the trailing edge of 

 the cylinder major modifications to the structure of the wake occur. 



*See discussion by Eringen on the paper by Lumley (p. 944). 



999 



