Citation

Bruun P. Journal of Geophysical Research: Oceans 1963; 68(4): 1065-1078.

Copyright

(Copyright © 1963, William Byrd Press for John Hopkins Press)

DOI

10.1029/JZ068i004p01065

PMID

unavailable

Abstract

This paper deals with longshore current theories. It gives a brief review of breaking waves including theoretical, laboratory, and field results. The longshore current theory based on the momentum inflow over a uniformly sloping beach and bottom is discussed, with special reference to the factor of friction. Two new longshore current theories, both based on the continuity principle, are also discussed. In one theory, recognized as the rip current approach, it is assumed that water thrown in by breaking waves runs seaward in rip currents, and this theory will perhaps be valid for profiles with well-developed bars and waves approaching the shore almost perpendicularly. In the other theory, the water from a wave which breaks under an angle with the bar flows in with a certain time lag along the bar. This apparently creates a longshore head difference and, therefore, a longshore current as well. The water may return to sea uniformly as undertow or in rip currents. This theory is particularly valid for waves breaking at a certain angle with the bar. In both cases, the momentum in the breaking waves is ignored because field observations show that in a well-developed bar profile most of the momentum has disappeared inside the bar following the breaking of the wave. Examples of computation of current velocities are given.

Keywords: Drowning; Drowning Prevention; Water Safety

Language: en