T.M. No. 68 (Continued) 



alongshore wave energy is worked out. This relationship is in 

 substantial agreement with one derived earlier from data for a 

 portion of the Florida Coast (see BEB T.M. No. 42). 



T.M. No. 69 - December 1954 



Wave Forces on Piles: A Diffraction Theory by R. C. MacCamy 

 and R. A. Fuchs 



An exact mathematical solution is presented for the linearized 

 problem of water waves of small steepness incident on a circular 

 cylinder. In addition to the formal mathematical treatment, some 

 simple deductions, based on the assumption of very small ratio of 

 cylinder diameter to incident wave lengths, are made. Suggestions 

 for possible extension of the theory to more extreme wave conditions 

 and other obstacle shapes are also presented. Application of the 

 theory to computation of actual wave forces on cylindrical piles is 

 attempted for tests performed in a small wave channel, and agreement 

 is found to be quite good in the region for which the assumptions 

 of the theory are fairly closely realized. 



T.M. No. 70 - December 1954 



The Effect of Fetch Width on Wave Generation 

 by Thorndike Saville, Jr. 



A method is presented for determining the effect of fetch width 

 on wave generation, primarily for use in predicting wave characteris- 

 tics in inland waters. Use of this method with actual fetch shapes 

 where the fetch is limited in a direction coincident with the wind 

 direction but stretches out longer in directions at an angle to the 

 wind, could result in an effective fetch length actually greater 

 than the (limited) distance in the direction of the wind due to 

 added angular components. Normally, however, use of the method 

 would be expected to result in a lesser effective fetch length. 



T.M. No. 71 - Apri I 1955 



Re-Analysis of Existing Wave Force Data on Model Piles 

 by R. C. Crooke 



This report presents an examination of previous work on this 

 subject and attempts to reconcile inconsistencies observed therein 

 by using a somewhat different method of analysis. 



Z\ 



