{"id":381227,"date":"2024-08-30T17:14:03","date_gmt":"2024-08-30T17:14:03","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/aqwa-hydrodynamic-diffraction-non-symmetry-in-the-ship-added-mass-matrix\/"},"modified":"2024-08-30T17:14:03","modified_gmt":"2024-08-30T17:14:03","slug":"aqwa-hydrodynamic-diffraction-non-symmetry-in-the-ship-added-mass-matrix","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/aqwa-hydrodynamic-diffraction-non-symmetry-in-the-ship-added-mass-matrix\/","title":{"rendered":"AQWA Hydrodynamic Diffraction \/ Non-symmetry in the ship added mass matrix"},"content":{"rendered":"<p>&lt;p&gt;I modeled a symmetrical ship hull in the xz plane using Aqwa to determine the hydrodynamic coefficients for added mass and potential damping. I imported the geometry into Design Modeler and aligned the xy plane with the waterline, setting the plane&#8217;s origin at the ship&#8217;s centerline. I divided the hull geometry into two sections&mdash;dry and wet&mdash;and successfully created a mirrored mesh, ensuring that the port side mesh was symmetrical to the starboard side. After reimporting the geometry into Aqwa, I added a mass point. As well explained in Faltinsen&#8217;s book, for the case without forward speed, the relations Aij = Aji and Bij = Bji must be respected. However, in my model, this is not observed for all terms. As examples are the terms A35 and A53:&lt;br&gt;<img decoding=\"async\" src=\"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2024\/08\/30-08-2024-1725036702-mceclip0.png\" \/>&lt;br&gt;<img decoding=\"async\" src=\"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2024\/08\/30-08-2024-1725036722-mceclip1.png\" \/>\\&lt;\/p&gt;&lt;p&gt;&lt;span class=&#8221;HwtZe&#8221; lang=&#8221;en&#8221;&gt;&lt;span class=&#8221;jCAhz ChMk0b&#8221;&gt;&lt;span class=&#8221;ryNqvb&#8221;&gt;Does anyone know why the symmetry of the matrix is \u200b\u200bnot respected?&lt;br&gt;Thanks in advance.&lt;br&gt;&lt;br&gt;Wave directions: -180 to 180 \/ number of directions: 9&nbsp;&lt;br&gt;Wave periods: 180s to 2s \/ number of periods: 21&nbsp;&lt;br&gt;Ship length: 55m&nbsp;&lt;br&gt;Mesh size: 0.4m&lt;br&gt;&lt;\/span&gt;&lt;\/span&gt;&lt;\/span&gt;&lt;\/p&gt;<\/p>\n","protected":false},"template":"","class_list":["post-381227","topic","type-topic","status-publish","hentry","topic-tag-added-mass-1","topic-tag-ansys-aqwa","topic-tag-hydrodynamic-diffraction"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_author_ip":["177.131.167.16"],"_btv_view_count":["334"],"_bbp_topic_status":["unanswered"],"_bbp_notification_enabled":["438961","438961","438961","438961","438961","438961","438961","438961","438961","438961","438961","438961","438961","438961","438961","438961"],"_bbp_subscription":["180344","438961"],"_bbp_topic_id":["381227"],"_bbp_forum_id":["27792"],"_bbp_engagement":["180344","438961"],"_bbp_voice_count":["2"],"_bbp_reply_count":["2"],"_bbp_last_reply_id":["389858"],"_bbp_last_active_id":["389858"],"_bbp_last_active_time":["2024-10-15 17:49:27"]},"test":"pohigorgmail-com"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/381227","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics"}],"about":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/types\/topic"}],"version-history":[{"count":0,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/381227\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=381227"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}