Transport analysis of solid sediments in a ballast water flow

Abstract

Abstract The ballast waters, necessary for the stabilization of the ships, move with it and are often discharged into marine environments sensitive to non-native organisms and transport polluting sediments capable of altering the balance of the local ecosystem. In this work, the transportability of particles smaller than 1 mm in size is studied by experimental analysis and the velocity field, generated by the flow, is detected by means of an image acquisition system. The work is developed with an experimental method using a variable flow rate hydraulic circuit equipped with a transparent duct capable of allowing optical access. The measurements of the motion of the particles, acquired by means of the fast photography system, along a section of the transparent duct are analyzed near the sedimentation area. By means of an image processing the frequency of the particles, crossing trough the reference section is detected. The data processing by FFT provides the average flow rate of the sediments and allows quantizing the particles transport according to the different hydrodynamic conditions imposed.