LABORATORY AND FIELD EXPERIMENTS AND DEVELOPMENT OF NUMERICAL NUMERICAL MODEL FOR 3-D FLUID MOTION AND SEDIMENT MOVEMENT DUE TO WAVE BREAKING

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TWO-DIMENSIONAL SUSPENDED SEDIMENT DISTRIBUTION CAUSED BY WAVE BREAKING ON A SLOPE WAS MEASURED IN A LABORATORY WAVE FLUME BY USING A CT TYPE SEDIMENT METER. THE 2-DIMENSIONAL SEDIMENT CONCENTRATION WAS OBTAINED FROM ATTENUATION RATE OF TRANSMITTED LASER POWER. IT WAS CONFIRMED THAT CONCENTRARION CAN BE QUANTITATIVELY EVALUATED. SIZE AND MOVEMENT OF SUSPENDED SEDIMENT CLOUDS WERE INVESTIGATED.THREE-DIMENSIONAL FLUID MOTION CAUSED BY WAVE BREAKING WAS MEASURED IN A LARGE WAVE FLUME BY USING AN ARRAY OF ACOUSTIC DOPPELAR VELOCIMETERS. VELOCITY VECTORS AND VORTICITY WERE CALCULATED FROM MEASURED DATA. TURBULENCE BY LOCAL EDDIES AND TURBULENCE PROPERTIES WERE INVESTIGATED. IT WAS FOUND THAT STRENGTH OF HORIZONTAL VORTICES INCREASE, THEN DECREASE WITH BREAKING WAVE PROPAGATION AND VERTICAL VORTICES ARE RELATIVELY WEAK NEAR THE BREAKING POINTS. VORTICITY BECOMES HOMOGENIOUS IN THE INNER SURF ZONE.IN ORDER TO EVALUATE INTERMITTENCY AND THREE-DIMENSIONALITY OF ORGANIZED EDDIES IN THE SURF ZONE, FIELD EXPERIMENTS WERE CONDUCTED WITH AN OBSERVATION ARRAY OF VELOCIMETERS AND SEDIMENT METERS. IT WAS FOUND THAT VELOCITY ACCERELATION AND TURBULENCE SHOW HIGH CORRELALTION AND CORRELATION BETWEEN THESE PROPERTIES AND SEDIMENT CONCENTRAION IS ALSO HIGH. INTERMITTENCY OF SEDIMENT PICKUP BY WAVE BREAKING WAS SHOWN AND THE PICKUP EVENTS COULD BE DETECTED BY FLUID VELOCITY AND ACCERELATION.