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

利用CT型泥沙测定仪，在实验室波浪水槽中测量了A坡波浪破碎引起的二维悬浮泥沙分布。由激光功率衰减率得到二维含沙量。证实了浓度是可以定量评价的。对悬浮泥沙云的大小和运动进行了研究，利用声学DOPPELAR流速仪测量了大型波浪水槽中波浪破碎引起的三维流体运动。根据测量数据计算了速度矢量和涡量。研究了局部旋涡引起的湍流和湍流特性。结果表明，随着破碎波的传播，水平涡的强度先增大后减小，破裂点附近的垂直涡相对较弱。内浪带涡度趋于均匀，为了评价内浪带有组织涡旋的间歇性和三维性，用VELOCIMETS和泥沙计组成的观测阵列进行了现场试验。结果表明，流速加速度与湍动高度相关，与泥沙浓度的相关性也很高。波浪破碎增沙具有间歇性，通过流速和加速度可以检测到增沙事件。

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.