Discussion. 3: Wave Processes

3.1 Analysis of oblique wave transmission at smooth and rubble mound structures

A KOtta

3.2 Validity of the non-linear shallow water equations for wave runup and reflection

KHu

Discussion to paper 3.1

Marcel van Gent (Delft Hydraulics) -Your analysis indicates an important influence of wave-generated currents on the incident waves for oblique attack In conventional physical model tests in a wave basin, there must be some form of return flow. Did you analyse the magnitude and influence of the return flow on the wave field, in particular on

the incident waves.

Response to Marcel van Gent by the authors To discuss the effect of the current in the physical model tests and the field, it is easier to think of the two components of the current, i.e. the onshore-offshore and the longshore currents generated by obliquely incident waves. Both these currents can indeed be different in the conventional physical model tests than in the field situation. Going first to the onshore-offshore current, this current in the basin can be relatively larger if the end of the basin invokes a no flux condition. However, during the model tests used in this paper water was allowed to spill over the end of the basin so as to maintain a constant level. As a close approximation to these physical model tests, an open flux boundary was used at the end of the basin in the numerical model. This condition results in a reduced return current compared to the case of a closed boundary. An openflux boundary in the cross-shore direction may be more typical of the field situation where the finite length of the breakwaters may result in reduced return current in the cross-shore direction along the breakwater.