静水中抛泥过程泥沙云团下落运动机理研究

Motion mechanism of particle clouds formed by dumping dredged material into quiescent water

采用双流体模型研究了抛泥过程中泥沙云团下落运动机理,并通过实验验证了模型的合理性.试验图像表明,双流体模型比单流体模型更适合于这类问题的模拟.数值仿真发现,完整的泥沙云团下落过程可以分为3个阶段:加速下沉阶段、减速下沉阶段、渐近稳定下沉阶段.前两个阶段表现为水与整个云团的相互作用,类似于各向同性异重流,后一阶段表现为泥沙颗粒自然沉降.泥沙云团在加速下沉阶段所引起水的对称涡与泥沙云团的运动是不同步的,对称涡是引起泥沙云团扩散的重要因素.

The motion of particle clouds formed by dumping dredged material into quiescent waters was numerically studied with two-fluid model, and the model was experimentally examined. Experimental photos show that two-fluid model is more appropriate than one-fluid model. Experimental and numerical results show that the entire particle clouds motion includes three phases： speedups descend stage, slowdowns descend stage and asymptotic steady descend stage. At the first two phases, the motion of particle clouds shows interaction between water and sand, particle clouds can be described as isotropic buoyant fluid; at the third phase, the motion of particle clouds is natural descend. The symmetry vortex of water induced by particle clouds does not synchronize with the motion of particle clouds, and the symmetry vortex is the key reason for clouds to disperse.