{"id":1557,"date":"2011-05-26T21:24:48","date_gmt":"2011-05-26T21:24:48","guid":{"rendered":"http:\/\/www.joswassink.nl\/insight\/?p=1557"},"modified":"2011-05-26T21:24:48","modified_gmt":"2011-05-26T21:24:48","slug":"tall-ships-in-tight-spots","status":"publish","type":"post","link":"https:\/\/www.joswassink.nl\/insight\/?p=1557","title":{"rendered":"Tall ships in tight spots"},"content":{"rendered":"<div id=\"attachment_1558\" style=\"width: 310px\" class=\"wp-caption alignleft\"><a rel=\"attachment wp-att-1558\" href=\"http:\/\/www.joswassink.nl\/insight\/?attachment_id=1558\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-1558\" class=\"size-thumbnail wp-image-1558\" title=\"ship\" src=\"http:\/\/www.joswassink.nl\/insight\/wp-content\/uploads\/2011\/05\/ship-300x196.jpg\" alt=\"\" width=\"300\" height=\"196\" \/><\/a><p id=\"caption-attachment-1558\" class=\"wp-caption-text\">HTC-ship model during manoeuvring test. (Photo: Marin)<\/p><\/div>\n<p><strong>Increases in both ship sizes and traffic density in harbours necessitate  better manoeuvrability of modern ocean giants. PhD researcher Serge  Toxopeus improved manoeuvring simulations considerably, thus paving the  way for less unwieldy designs.<\/strong><\/p>\n<p>Simulations of a ship performing special manoeuvres like steering  alternatively full port and starboard for about a minute, or steering  full rudder and making a 360-degree turn, can go painfully wrong. In  examples quoted by PhD researcher, Serge Toxopeus, the simulation  underestimated deviations from the zigzag course by almost 30 percent,  while overestimating the diameter of the narrowest turn by 46 percent.<!--more--><\/p>\n<p>Toxopeus,  who after graduation from TU Delft in 1996 went to work at the Maritime  Research Institute Marin in Wageningen, set out to prove that the  simulation could be improved if different input data were used.<\/p>\n<p>Traditionally,  the input data describing the forces and moments on the ship&#8217;s hull are  based on measurements made of a scale model in a large tank. It&#8217;s  perhaps a bit confusing that what seems to be a calculation &#8211; a  simulation &#8211; is in fact based on empirical data, but so it is.  Nonetheless, tank tests provide a set of parameters that are used in  simulations to calculate the forces on the ship&#8217;s hull and, hence, its  trajectory through the water and manoeuvrability.<\/p>\n<p>Alternatively,  one can calculate the forces on the hull under a certain course using  computational fluid dynamics (CFD). Progress made in software and  computing power now render this a feasible approach, although it still  typically requires a couple of days to evaluate a hull design. Toxopeus  has used both a physical and numerical model of a large container ship,  called Hamburg Test Case (or HTC), to evaluate this numerical approach.<\/p>\n<p>He  found that simulations based on the CFD data corresponded better with  the tank tests than those based on empirical parameters. This means that  a ship&#8217;s manoeuvring behaviour can be forecast much more reliably while  still under design, thanks to CFD.<\/p>\n<p>Does that mean that tank  tests will become obsolete for testing ship designs? Absolutely not,  says Professor Rene Huijsmans (Mechanical, Maritime and Materials  Engineering), who was Toxopeus&#8217; PhD supervisor. \u201cCFD was used by  Toxopeus in addition to tank tests, to determine a couple of parameters,  which then could be used in a simulation. But to replace the entire  tank test by CFD calculations is of another magnitude entirely, and way  beyond today&#8217;s computational power.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Increases in both ship sizes and traffic density in harbours necessitate better manoeuvrability of modern ocean giants. PhD researcher Serge Toxopeus improved manoeuvring simulations considerably, thus paving the way for less unwieldy designs. Simulations of a ship performing special manoeuvres like steering alternatively full port and starboard for about a minute, or steering full rudder [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3,6],"tags":[85,387,391],"class_list":["post-1557","post","type-post","status-publish","format-standard","hentry","category-articles","category-delta","tag-cfd","tag-ship-design","tag-simulation"],"_links":{"self":[{"href":"https:\/\/www.joswassink.nl\/insight\/index.php?rest_route=\/wp\/v2\/posts\/1557","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.joswassink.nl\/insight\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.joswassink.nl\/insight\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.joswassink.nl\/insight\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.joswassink.nl\/insight\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1557"}],"version-history":[{"count":0,"href":"https:\/\/www.joswassink.nl\/insight\/index.php?rest_route=\/wp\/v2\/posts\/1557\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.joswassink.nl\/insight\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1557"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.joswassink.nl\/insight\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1557"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.joswassink.nl\/insight\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1557"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}