Discussion on Papers 4–6

PAPER 4

MR N. W. H. ALLSOP, Hydraulics Research Limited, Wallingford

How does the Author couple external flows to internal flows without a physical model? Can one continue to use the continuum assumption?

Laboratory experiments appear to show very large hydraulic gradients. Is field or laboratory information available on the flow performance (and its variability) in real breakwater cores under these very steep gradients?

DR S. S. L. HETTIARACHCHI, University of Moratuwa, Sri Lanka

Could the Author state the form of the expression adopted in the model for the hydraulic gradient for flow through porous media? It is presumed that both drag and inertia terms were included.