Theoretical breaking criteria for progressive surface gravity
waves are examined, and laboratory and field experiments concerned
with breaking waves are reviewed with respect to the testing of these
breaking criteria. The measurements of Komar and Simmons are
presented here for the first time. Only three theoretical breaking
criteria have been proposed for maximum steady waves in water of
constant depth: (1) the kinematic breaking criterion, in which the
horizontal partical velocity at the crest just equals the wave phase
velocity, (2) the reversal of the vertical particle velocity near the
crest as the ratio of wave height to water depth, H/h, increases,
and (3) the reversal of the vertical pressure gradient beneath the
crest as H/h increases. Although most theoreticians have applied
the kinematic breaking criterion in conjunction with relatively simple
wave theories (based on the motion being inviscid, irrotational,
incompressible, surface tension free, and two dimensional), they do
not always obtain identical results; for example, theoretical estimates
of the particle acceleration at the crest range from zero to g,
the gravitational acceleration. For shoaling waves, the kinematic
breaking criterion and the presence of a vertical surface are suggested
as breaking criteria. Unfortunately, these criteria were
applied to the long wave theory which is considered inadequate near
the breaking position.
The re-examination of experiments on breaking waves shows
that past measurements are not sufficient for testing any of these
breaking criteria. In particular, the following improvements should
be made: (1) standardize definitions of wave and breaking parameters,
(2) apply or design, if necessary, more accurate techniques
to measure water particle velocities and accelerations, and
(3) monitor the fluid motions from which the breakers cannot be
separated (e.g. backwash, solitons, reflected waves, edge waves
and rip currents). Studies specifically designed to obtain the
necessary measurements for testing the theoretical breaking
criteria are needed. / Graduation date: 1974
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/28657 |
| Date | 08 June 1973 |
| Creators | Gaughan, Michael Kenneth |
| Contributors | Komar, Paul D. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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