2 The Model 



Model-Prototype Scale Relationships 



Tests were conducted at a geometrically undistorted scale of 1:24, model to 

 prototype. Scale selection was based on the sizes of model armor available 

 compared with the estimated size of prototype armor required for stability, 

 preclusion of stability scale effects (Hudson 1975), and capabilities of the 

 available wave tank. Based on Froude's model law (Stevens 1942) and a 

 linear scale of 1:24, the following model-prototype relations were derived. 

 Dimensions are in terms of length (L) and time (T). 



Characteristic 



Dimension 



Model-Prototype Scale Relation 



Length 



L 



L r = 1:24 



Area 



L 2 



A r = L r 2 = 1:576 



Volume 



L 3 



V r =L r 3 = 1:13824 



Time 



T 



T r = L, 172 1 :4.90 



The specific weight of water used in the model was assumed to be 

 62.4 pcf, compared to that of seawater, 64.0 pcf; also, specific weights of 

 model revetment construction materials were not the same as their prototype 

 counterparts. These variables were related using the following transference 

 equation: 



KL 



W. 



M 



3 



"w, ■ 



- 1 



W, 



w. 



W- 



- 1 



W a = weight of an individual armor unit, pounds 

 m, p = model and prototype quantities, respectively 

 y a = specific weight of an individual armor unit, pounds per cubic foot 



Chapter 2 The Model 



