platform supported by battered piling would probably be carried out by establishing a 

 Stream-function or other wave theory representation for the particular wave conditions 

 selected for design. 



On occasion, it may be desired to interpolate between the cases presented in the tables 

 for wave conditions that are substantially different from any of the 40 cases. Several 

 numerical and graphical interpolation methods were explored with a goal of obtaining a 

 simple method which yielded reasonably accurate results. Because most wave variables of 

 interest are nonUnear, numerical schemes which used linear interpolation proved to be 

 inaccurate. The best procedure was found to be a simple graphical procedure which 

 generally yields results within 5 percent. 



Method 



The method uses the tabulated parameters of interest for the H/H^ values above and 

 below the value of interest at the two lower and two higher h/L^ tabulated values; in all 

 for each parameter desired, the interpolated value is based on values of that parameter for 

 eight tabulated wave conditions. The method is outlined in the following paragraphs and 

 illustrated by two examples. 



Suppose that the wave height, period, and water depth selected for design are Hjy, T^), 

 and hjy. The design wave steepness and relative depth are calculated as: 



Wave Steepness: = 



LoD 



Relative Depth: 

 where 



^D 



OD 



The relative depth and wave steepness are plotted on Figure 40 to estabUsh which wave 

 cases should be used for design. For the example shown, H/h^ = 0.086 and 

 h/L^ = 0.313. This point falls between H/Hg values denoted as B and C (i.e., 50 and 75 

 percent of breaking heights, respectively) and between tabulated h/L^ values denoted as 

 Cases 7 and 8. The interpolation would therefore be based on the tabulated parameter of 

 interest for Cases 6-B, 6-C, 7-B, 7-C, 8-B, 8-C, 9-B, and 9-C. 



The interpolation proceeds as follows. An auxiliary plot is made of the variable of 

 interest, e.g., the total dimensionless drag force at = 0° [denoted F£j(0°, Surf.)]. This plot 

 provides a continuous distribution of F^(0°, Surf.) versus h/L^ for relative breaking 

 heights B and C. Interpolated Fj^ values are tlien obtained from the auxiliary plot for 

 the h/L^ design value (0.313). The interpolation for the design wave steepness requires 



88 



