Recently, new laboratory experiments on wave shoaling have been made 

 by Svendsen and Buhr-Hansen (1977)^3 and Flick (1978)7^. Some experimental 

 results are shown in Figure 85 where it is again apparent that linear wave 

 shoaling theory is far from correct. Most existing radiation stress models 

 use linear shoaling theory to estimate wave height fields. The errors 

 resulting could be excessive. Svendsen and Hansen utilized laboratory 

 equipment with a special flap-type wave generator that eliminated free 

 second harmonies in the wave profile. Test of the Boussinesq theory up 

 to the breaking limit is an active research area and the boundary shear 

 stresses must be included in the theory to affect a fair comparison. In 

 this regard, Svendsen and Buhr-Hansen (1978)75 have shown that 



(1) Both wave height and profile show good agreement near break- 

 ing even though the H/h ratio is large; 



(2) wave setdown is adequately described; and 



(3) the horizontal velocity "... shows remarkably good agree- 

 ment even at the breaking point ..." with measured values. 



The theoretical results were obtained analytically and not by numerical 

 methods. 



Field shoaling data for irregular waves are also needed to test the 

 Boussinesq theory. The nonlinear process resulting in transfer of energy 

 from the dominant frequency to harmonics via strong interactions is further 

 discussed by Guza and Thornton (1978) where some field results are presented. 



2. Two-Dimensional Tests . 



Abbott, Petersen, and Skovgaard (1978) were primarily interested in 

 testing the accuracy of their numerical model in two dimensions. For this 

 purpose they duplicated a series of well-documented physical model experi- 

 ments of the Danish harbor at Hanstholm. Because of the uncertainties 

 associated with periodic wave tests, irregular waves based upon field- 

 measured, time series of water surface elevations at the harbor entrance 

 were employed. This illustrated the fact that numerical models can be 



''^SVENDSEN, I. A., and BUHR-HANSEN, J., "The Wave Height Variation for 

 Regular Waves in Shoaling Water," Coastal Engineering, Vol. 1, 1977, 

 pp. 261-284 (not in bibliography). 



'"+FLICK, R.E., "Study of Shoaling Waves in the Laboratory," Ph.D. 

 Dissertation, S.I.O., University of California, San Diego, 1978 

 (not in bibliography) . 



^^SVENDSEN, I. A., and BUHR-HANSEN, J., "Prebreaking Behaviour of Waves 

 on a Beach," Euromeoh 102, University of Bristol, July 1978 (not in 

 bibliography) . 



213 



