Study of Ballast Water Exchange by Pumping-Through Method : Hydraulics Experiment by Using 3 Dimensional Model Tank

Abstract

Discharged baltast water from the ships has beenidentified as a potential threat to the marine environment ． Many species ofmarine animals and microorganisms ofspecies are included in discharged ballast water and these are transfbrred f セ om one port to others ． Breeding species have some potential that cause severe adverse impact on ecosystem including expulsion of native species ． It probab 畳 y affects the human society as well ． Therefbre ， the management of ballast water 菫 s important ．The ballast water exchange by using a Pumping − through method is one ofthe management ofballast water ． Authors have inspected the validity of this method by using a 2 − Dimension tank model and numerical calculation ． As a result ， we have seen that 95％ ofthe ballast water exchange is possible if seawater of3times ofballast tank capacity is overfiowed ． However ， the 2 − D tank model is different shape from an actua1 ballast tank ， Then ， we made a more real 3 − Dimensions tank modeL In this paper， we experimented w 萋 th the 3 − D 寝mk mode1 ， 1n the experiment ， we used the fluid dyed with methylene blue and measured the density ofthe fluid by an optical technique ． As a result， we obtained the same result the experiment result with 2− D tank mode1 ． Keywords ： ocean pollution ， ba〃ast water ， Pitmpin9 through method ，