Introducing Free Surface Scanning, an optical, non-contact technique for recording the deformed free surface in towing tank

Perissakis, SG; Grigoropoulos, GJ; Liarokapis, DE

dc.contributor.author	Perissakis, SG	en
dc.contributor.author	Grigoropoulos, GJ	en
dc.contributor.author	Liarokapis, DE	en
dc.date.accessioned	2014-03-01T02:51:44Z
dc.date.available	2014-03-01T02:51:44Z
dc.date.issued	2008	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/35610
dc.relation.uri	http://www.scopus.com/inward/record.url?eid=2-s2.0-84860011013&partnerID=40&md5=f991e7452a9406003ef2304661cff3b0	en
dc.subject.other	Field resolution	en
dc.subject.other	Free surfaces	en
dc.subject.other	Hull forms	en
dc.subject.other	Image processing technique	en
dc.subject.other	Its efficiencies	en
dc.subject.other	Measurement philosophy	en
dc.subject.other	Non-contact techniques	en
dc.subject.other	Special treatments	en
dc.subject.other	Wavefields	en
dc.subject.other	Image processing	en
dc.subject.other	Natural resources	en
dc.subject.other	Ocean engineering	en
dc.subject.other	Optical data processing	en
dc.subject.other	Optical recording	en
dc.subject.other	Ship model tanks	en
dc.subject.other	Uncertainty analysis	en
dc.subject.other	Yachts	en
dc.subject.other	Surfaces	en
dc.title	Introducing Free Surface Scanning, an optical, non-contact technique for recording the deformed free surface in towing tank	en
heal.type	conferenceItem	en
heal.publicationDate	2008	en
heal.abstract	In this paper, an innovative technique for measuring the wave field around a towed model is presented. This method, denoted as Free Surface Scanning (FSS) and developed in the towing tank of NTUA, is advantageous over the commonly used methods of similar field resolution, as it is optical and therefore non- intrusive, fast and accurate. The arrangement gives the flexibility to cope with almost every type of ship, including sailing yachts. The resolution and consequently the accuracy of the system can be adjusted depending on the needs of the experiments. Moreover, it incorporates the modern measurement philosophy for uncertainty analysis, while the cost and complexity of implementation is reasonable. It is based on the following concept:A stationary vertical laser- sheet, normal to the direction of model movement is produced underwater in the towing tank and illuminates a vertical cut of the water. The upper border of this cut represents a vertical cut on the free surface. As a towed model travels along the towing tank and passes through the laser-sheet, digital cameras capture sequentially luminous cuts, which represent sequentially cuts of the wave field around the model. Finally the captured images are filtered and analysed using image processing techniques. Applying special treatment and in combination with simple complementary techniques, the captured field is extended in some cases up to close vicinity of the hull surface. The implementation of the method is described and its efficiency is demonstrated via comparison with standard experimental methods.A typical hull form and a sailing yacht are used in this respect. © 2008 Taylor & Francis Group, London.	en
heal.journalName	Maritime Industry, Ocean Engineering and Coastal Resources - Proceedings of the 12th International Congress of the International Maritime Association of the Mediterranean, IMAM 2007	en
dc.identifier.volume	2	en
dc.identifier.spage	769	en
dc.identifier.epage	776	en