DISCUSSION OF RESULTS 



The ship speed Uq was used in plotting the velocity profiles in Figure 6 because the 

 data did not show a potential velocity U perceptibly different from Uq. The velocity profiles 

 are of the generalized parabolic shape. The only profiles showing unusual characteristics 

 are those at Station VI, which was located downstream of the overboard discharge. These 

 plots indicate a region of separation (probably caused by the lip on the overboard discharge), 

 and show the jet of fluid injected into this region by the overboard discharge. The velocity 

 profiles for Station VI are shown in Figure 6 and the data are given in Table 1, but no 

 boundary-layer parameters were calculated for this location because of the irregular nature of 

 the flow. 



A curve-fitting technique-^ was used to find the values of S and n given in Table 2, 

 with the assumption that the velocity profile was of the form 



^=(,/5)i/". [1] 



Except for the 5-knot condition, the values of 5 obtained are in quantitative agreement with 

 the small amount of existing data for corresponding Reynolds numbers. ^'^ 

 The expression for displacement thickness 



..-['(l-^)dy, [21 



can be used to obtain §* by graphical integration of the velocity profiles. Substituting 

 Equation [1] into Equation [2] and integrating from y = to y = 5 gives 



8* = -^ S. [3] 



71+1 



Alternative estimates of 5 which are tabulated as 8 (8*) were obtained using values of n from 

 the numerical analysis and values of S* from the graphical integration in Equation [3]. 

 The momentum thickness 



•^ 

 was also determined graphically from the experimental points and is given in Table 2. 



The values of n obtained show the effect of increasing Reynolds number, and are in 

 substantial agreement with the values given in Reference 3 for full-scale measurements on 

 the merchant ship SNAEFELL. These values also show agreement with extrapolated values 

 of n for the tests on friction planes reported in Reference 5. Schlichting^ also corroborates 

 the increase of n with increasing Reynolds number for pipes. 



(Text continued on page 11.) 



