22 



U = 1.0 knot R x = 2.5x10 



^=■ = 0.198 -^==0.03 R=43xl0 5 



0.03 R = 52 -77x10 



0.032" Trip Wire Around Girth- 



£ 



F 7 



U = 0.80 knot 

 4= = 0.158 



R x = 4.8x10 U = 2.0 -3.5 knots R„ = 5 -8.8x10 



R = 34xl0 5 4^ = 0.396-0.693 -g 1 = 0.003 R = 86-I50xl0 5 



Figure 16 - Boundary Layer Plow Conditions on Tanker Model 

 with Trip Wire as Turbulence Stimulator 



the greater flow velocity toward the turn of the bilge. This probably ex- 

 plains the observed pattern of transition shown in Figure l6 where it is seen 

 that transition occurs closer to the stem with increasing depth along the hull, 



Condition 4 - Stimulation by Sand Strip 



Data obtained from the boundary-layer survey made with the fine- 

 grain sand-strip are summarized in Figure 18. The pattern of the flow aft of 

 the sand strip at low speeds was found to be considerably different from that 

 obtained with the trip wire. 



COMPARISON OF EFFECTIVENESS OF VARIOUS STIMULATORS 



A summary of the boundary layer surveys made with the various meth- 

 ods of stimulation is given in Figure 19- Here it may be seen that the 1/8- 

 inch rod at 48 diameters is more effective in producing a turbulent boundary 

 layer than any of the other devices. However, it must be remembered that this 

 is a qualitative study and hence there is no guarantee that the intensity and 

 scale of turbulence induced by the rod are of the proper magnitude. Quanti- 

 tative determination of the intensity and scale of turbulence under basin 



