Investigations on the dynamics of particle clouds in stagnant water using response surface methodology

Abstract

Disposal of sediments during land reclamation and dredging is an important component in many environmental engineering projects. Dredged material can be discharged into the ambient water either instantaneously to form a particle cloud or continuously to form a slurry jet. This paper presents the results of laboratory experiments to understand the dynamics of particle cloud in stagnant water. Different independent parameters such as particle size, nozzle diameter, cumulative mass of sand particles, and release height were tested. Due to wide ranges of selected variables and interactions between parameters, response surface methodology (RSM) technique was employed to determine the importance and effectiveness of each parameter on the growth and motion of particle clouds. A narrow range of non-dimensional cloud buoyancy in thermal regime was selected for design of experiments. Particle size was found to be the most significant parameter for the response predictions. The RSM results showed that increasing the nozzle diameter from 5 mm to 14 mm slightly increased the cloud width if all other parameters were kept unchanged. Statistical analysis of results indicated that the effect of the release height on growth of particle cloud was not significant; however, it was effective on variations of frontal velocity.