Lines of constant wove 

 ^ conditions 



-Critical R e 



! R e 



Figure 47. Hypothetical sketch of relative runup 

 variations (scale effects) on a given 

 structure for sets of specified wave 

 conditions and varying Reynolds number. 



3. Smooth-Slope Scale Effects . 



Limited large-scale data for smooth slopes on a 1 on 10 bottom slope 

 are available (Saville, 1958; 1960). From this data and other appropri- 

 ate small-scale data, Figure 48 was prepared in the manner previously 

 discussed. The figure gives results only for dg/H^ = 1.5, because the 

 large-scale data were limited to a narrow range of dg/H^ values close 

 to dg/H^ = 1.5. Small-scale data used are from Saville (1955, 1956, 

 1958, 1960), and Hudson, Jackson, and Cuckler (1957). The small-scale 

 tests by Saville (1958) were one- tenth the scale of his large-scale 

 tests, and the geometrical arrangement was the same in both cases. 

 Savi lie's data are given in Table 20. The smooth slope was not modeled 

 exactly between scales, because plywood was used for both the small- 

 and large-scale tests and the small scale may have been proportionately 

 rougher. An attempt to closely model the slope roughness is discussed 

 later in this section. 



In the small-scale tests, the variability of results for the 1 on 3 

 slope is pronounced (Fig. 48). The range of runup values derived from 

 Hudson, Jackson, and Cuckler (1957) for Rg = 9 x lo 4 encompasses those 

 runup values of the largest scale (R e = 3.75 x 10 6 ) . Also, for the 

 1 on 3 slope, the data of Saville (1955) vary considerably between the 

 two Reynolds numbers, Rg = 6.3 x 10^ and 1.8 x io 5 . In contrast to the 

 1 on 3 slope, the 1 on 6 slope values show less variability. 



Comparisons in Figure 48 were not extended to lower wave steepnesses 

 because the large-scale test conditions were such that at low wave steep- 

 nesses, the waves were long relative to the bottom slope (t/L values of 

 0.21 and 0.30 were tested). However, even for the wave conditions given 

 in the figure, t/L values varied between certain experiments. Thus, 

 test conditions are similar but not necessarily the same. 



06 



