Vogel and Patterson 



some cases the addition of a long molecule polymer to a liquid resulted in higher 

 friction losses at low flow rates and lower friction losses at high flow rates. 

 This is analogous to the behaviour observed by Daily and Bugliarello (1961) in 

 wood fibre suspensions in smooth pipes. Shaver and Merrill (1959) observed the 

 velocity profiles of dilute polymer solutions in circular pipes and found that at 

 high flow rates the profiles were sharper than for a corresponding Newtonian 

 flow. This did not check with Dodge and Metzner's (1958) prediction of profiles 

 blunter -than -Neiwtonian. This disagreement was attributed by Dodge and Metz- 

 ner to the possible presence of elastic effects in the fluids used by Shaver and 

 Merrill. 



Recently Fabula, Hoyt and Crawford (1963) investigated about twenty-five 

 water-soluble polymers. They discovered that whenever the polymer had both a 

 high molecular weight and a linear molecule, significant reduction in friction 

 occurred in the high Reynolds number flows (Re > 10^). This phenomenon was 

 first observed with a rotating-disc apparatus and later confirmed using a pipe 

 flow apparatus. The very dilute solutions studied were often superficially indis- 

 tinguishable from plain water, and their apparent viscosities for the high shear 

 rates involved were nearly that of water. 



One of the polymers tested in the rotating disc apparatus, poly(ethylene 

 oxide), gave about a 70% torque reduction for a .01% solution (Hoyt and Fabula 

 1964). In the pipe flow apparatus, cases of 50% pipe friction reduction were 

 found for very dilute solutions of poly(ethylene oxide) in water (Fabula, 1963). 

 Because of these large changes in the turbulent flow produced by very low con- 

 centrations of poly(ethylene oxide) in water, it was proposed to study the effect 

 of these polymer solutions when they were injected into the boundary layer of an 

 underwater body. 



EXPERIMENTAL APPARATUS 



There are a number of variables which should be considered when a fluid is 

 injected into the boundary layer of a body. These are: 



1. Type of polymer solution 



2. Concentration of the polymer solution 



3. Velocity of injection of the solution 



4. Position of the injection slot 



5. Tunnel velocity 



A body of revolution (Fig. 1) was chosen as the most convenient to use for 

 these exploratory experiments. Because our low-turbulence water tunnel has a 

 working section 35cm by 35cm, the maximum diameter of the body was limited 

 to about 5cm so that tunnel blockage would be minimized. The body as finally 

 constructed was 41.3cm long and had a maximum diameter of 5.08cm. Five slots 

 were made in the body; the positions of the slots are shown in Fig. 2. The section 



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