Modelling and numerical/experimental investigation of granular cargo shift in maritime transportation

Spandonidis, Christos

dc.contributor.author	Spandonidis, Christos	en
dc.date.accessioned	2016-09-27T07:25:15Z
dc.date.available	2016-09-27T07:25:15Z
dc.date.issued	2016-09-27
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/43643
dc.identifier.uri	http://dx.doi.org/10.26240/heal.ntua.2375
dc.rights	Default License
dc.subject	granular material	el
dc.subject	molecular dynamics	en
dc.subject	cargo shift	en
dc.subject	ship stability	en
dc.subject	capsize	en
dc.title	Modelling and numerical/experimental investigation of granular cargo shift in maritime transportation	en
dc.contributor.department	Τομέας Μελέτης Πλοίου και Θαλασσίων Μεταφορών	el
heal.type	doctoralThesis
heal.classification	marine engineering	el
heal.classification	Mathematical methods, programming models, simulation modelling	el
heal.language	en
heal.access	free
heal.recordProvider	ntua	el
heal.publicationDate	2016-08-30
heal.abstract	The study of granular materials (powders, sands, grains, metal ore etc.) should be a topic of great interest in naval architecture, since cargo shift represents a major hazard for ship safety and probably the most common cause of capsize of large ships. Despite though its great importance, the behaviour of granular cargos transported by sea has not been sufficiently investigated yet from a theoretical perspective. As a result, international regulations governing the procedures of loading and stowage of bulky cargos, while continuously updated and improved, remain mainly empirical. In the current Thesis, a micro-scale modelling approach is presented, aimed to develop capability for simulating the dynamic behaviour of granular materials having physical properties conforming to those of bulky cargos commonly transported through the sea, inside ship holds. The well-established method of “Molecular Dynamics” is employed for modelling particles’ interactions and for predicting macroscopic features of the excited granular material behaviour. The algorithm is further combined with standard models of ship motion, in order to understand the interplay of granular material flow with vessel motion. At the first stage, “dry” granular materials comprised of spherical particle and affected by non-linear frictional forces are employed. Later, a number of improvements are incorporated, to bring the model closer to reality, by introducing the effect of environmental humidity and also the irregularity in particles’ shape. To discern qualitatively different patterns of behaviour, a variety of materials and filling ratios have been examined. Moreover, to improve performance, the computational algorithm was parallelized for Graphical Processing Unit (GPU) implementation and the merit of it was properly evaluated. Characteristic simulation results of a 2D rectangular scaled barge, partly filled with bulky cargo and vibrated in roll, sway and heave are included in the Thesis. The barge is, either, forced to oscillate in a prescribed motion; or is free to move under the effect of wave loads and her cargo’s occasional fluid-like movement. Critical parameter values where cargo shift is initiated are identified. The intention has been to maintain the excitation amplitudes and frequencies close to realistic open sea conditions although the scaling problem is in itself a major scientific challenge. Judging from the qualitative character of the obtained results and also from comparisons of some key findings with experimental results, it appears that the described simulation model has good potential to evolve into a useful and practical computational tool for the investigation of stability of ships carrying solid cargos in bulky form.	en
heal.advisorName	Spyrou, Kostantinos	el
heal.committeeMemberName	Athanasoulis, Gerasimos	en
heal.committeeMemberName	Papanikolaou, Apostolos	en
heal.committeeMemberName	Papadopoulos, Christos	en
heal.committeeMemberName	Georgiou, Ioannis	en
heal.committeeMemberName	Krokida, Magdalini	en
heal.committeeMemberName	Stavropoulou, Maria	en
heal.committeeMemberName	Spyrou, Kostantinos	en
heal.academicPublisher	Σχολή Ναυπηγών Μηχανολόγων Μηχανικών	el
heal.academicPublisherID	ntua
heal.numberOfPages	207
heal.fullTextAvailability	true