NOTICE OF PUBLICATION FOR m\'J ICTHOD OF DRAINING 

 WAVE REFRACTION DIAGRAMS 



The Board wishes to call the attention of coastal engineers to an 

 article on a new method of draT-ri-ng wave refraction diagrams published in 

 the Transactions of the American Geophysical Union , Volume 33, Number 6, 

 December 195 2 « The article, entitled "The Direct Construction of Wave 

 Rays" is by R. S. Arthur, W, H« Ifank, and J<, D, Isaacs, 



The method eiiploys a new type of overlay shon-ni in Figure 1. The use 

 of this overlay for ordinary cases (a less than 80 ) is shoxm in Figure 2, 

 From the wave period, values of C-./Gp for each contour interval may be 

 conputedo (C is the wave velocity, ,gna the subscript 1 refers to the first of 

 the txTO contours reached by the orthogonal, and the subscript 2 to the second, 

 In the usual case the first contour will be the one toward deeper wateij but 

 the method works equally well whether proceeding from deep to sha3J.ow water^ 

 or shallow to deep xirater). To construct the orthogonal, sketch in a mid- 

 contour between the two contours to be crossed, extend the orthogonal (in 

 its original direction) to tliis mid-contour, and construct a tangent to the 

 mid-contour at this point of intersectiono Lay the line (on the overlay) 

 labeled "orthogonal" along the incoming orthogonal xri.th the point marked. 1*0 

 at the intersection of orthogonal and raid-contour (see Figure 2a). Rotate 

 the tenplate about the "turning point" until the C^/C„ value corresponding 

 to the contour interval being crossed intersects trie tangent to the mid- 

 contouTo The turned orthogonal is drawn in this direction from a point 

 on the incoming orthogonal equidistsxit from the two contOTirs, when these 

 distances (from point to contours) are iiBasured along the incoming and 

 t^urned orthogonals (see Figure 2b), The line so drawn is the "incoming 

 orthogonal" for the next contour interval. 



There is no difference in R/J procedures, and Aa values for R/J and 

 G-/C- are graphed on the teitplatee An angular protractor has been put on 



the tenplate to aid in turning these angle So 



This new method of constructing refraction diagrams has been studied 

 and used by personnel of the Board, and it is felt that it represents, in 

 general, a sinpler and quicker nsthod of constructing refraction diagrams 

 than the older ones now generally in use, and xjith no sacrifice in 

 accuracy. 



