The small-scale and large-scale results for periodic waves are compared in Fig. B.1 and Fig. B.2. Figure B.1 shows the wave height variation and the set-up and Fig. B.2 shows the characteristics of the velocity field. The small flume has a rigid bed and the large flume a sandbed on which a breaker bar was formed. The variability in the large-scale results, amongst others the shift of the breakpoint during the first and second day, is related to the morphological development in these large-scale tests.