Dept. of Construction Engineering, University of São Paulo, Brazil.
Dept. of Naval and Ocean Engineering, University of São Paulo, Brazil.
Mar Pollut Bull. 2021 Jul;168:112399. doi: 10.1016/j.marpolbul.2021.112399. Epub 2021 Apr 28.
The sediments inside the ballast tanks might compromise the effectiveness of the ballast water exchange procedure. In the present study, the sediment removal from double bottom ballast tanks due to flow-through ballast water exchange is investigated by simplified experimental and numerical models. Two flow rates and two sediment densities were considered to verify their influence on the process. Besides, the effectiveness of two tank configuration modifications to improve the sediments removal was investigated. The first is the introduction of a flow deflector inside the tank and the second is the water inflow from the bottom. A fully Lagrangian particle-based method is adopted to simulate the sediment removal process with complex tank geometry. A new boundary condition is proposed to model the mesh of the bottom inlet in the bottom inflow configuration. Despite the simplifications of the numerical model, the computational results are in good agreement with the experimental ones. The results show that the flow-through ballast water exchange method might not be effective to remove the sediments entrapped between the bottom stiffeners, and the proposed modifications, despite challenging implementation, improve the sediment removal.
压载舱内的沉积物可能会影响到压载水更换程序的有效性。在本研究中，通过简化的实验和数值模型研究了由于流经式压载水交换而从双底压载舱中清除沉积物的过程。考虑了两种流速和两种沉积物密度，以验证它们对该过程的影响。此外，还研究了两种舱室配置修改以提高沉积物清除效率的效果。第一种是在舱内引入流量挡板，第二种是从底部进水。采用完全拉格朗日基于颗粒的方法模拟具有复杂舱室几何形状的沉积物清除过程。提出了一种新的边界条件来模拟底部进水配置中底部入口的网格。尽管数值模型进行了简化，但计算结果与实验结果吻合良好。结果表明，流经式压载水交换方法可能无法有效地清除困在底部加强筋之间的沉积物，而所提出的修改方案虽然实施具有挑战性，但可以提高沉积物清除效率。
