{"id":37251,"date":"2019-08-21T09:46:56","date_gmt":"2019-08-21T09:46:56","guid":{"rendered":"\/forum\/forums\/topic\/ansys-aqwa-mud-layer-stiffness\/"},"modified":"2019-08-21T09:46:56","modified_gmt":"2019-08-21T09:46:56","slug":"ansys-aqwa-mud-layer-stiffness","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/ansys-aqwa-mud-layer-stiffness\/","title":{"rendered":"ANSYS Aqwa &#8211; Mud Layer Stiffness"},"content":{"rendered":"<p>In AQWA Theory Manual the mud layer springs&nbsp;don&#8217;t seem to provide a continuous force-displacement law. For simplicity let&#8217;s considere the viscous spring force. In this case, the damping force is such that (k -&gt; constant; v -&gt; node velocity):<\/p>\n<p><\/p>\n<ul><\/p>\n<li>0, if the node is above mud line<\/li>\n<p><\/p>\n<li>k x v, if the node is below the seabed<\/li>\n<p><\/p>\n<li>k x v x sin(theta)^2, in between<\/li>\n<p>\n<\/ul>\n<p><\/p>\n<p>Now, the theta variable is defined from the water depth (d), the mud layer thickness (z) and the node position (zj):<\/p>\n<p><\/p>\n<p><img decoding=\"async\" src=\"https:\/\/us.v-cdn.net\/6032193\/uploads\/attachments\/a79b0405-3e04-437d-bba1-aa9c0101ce91\/08e9a128-3d57-4b53-a346-aab000a0083e_eq.jpg?width=690&amp;upscale=false\" alt=\"\"><\/p>\n<p><\/p>\n<p>So, let&#8217;s assume d=200 [m] and an unitary mud layer. In this case, for the point near the seabed and near the top of the mud layer, respectively:<\/p>\n<p><\/p>\n<ul><\/p>\n<li>zj=-200 -&gt; theta=0 -&gt; sin(theta)^2=0 -&gt; F=0<\/li>\n<p><\/p>\n<li>zj=-d+z -&gt; theta=pi\/2 -&gt; sin(theta)^2=1 -&gt; F= k x v<\/li>\n<p>\n<\/ul>\n<p><\/p>\n<p>So it seems the law provided is not connecting to the under seabed and above mud line regions in the proper way.<\/p>\n<p><\/p>\n<p>&nbsp;<\/p>\n<p><\/p>\n<p>Is this correct?<\/p>\n<p><\/p>\n<p>Thanks in advance<\/p>\n","protected":false},"template":"","class_list":["post-37251","topic","type-topic","status-closed","hentry"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_old_topic_id":["9427"],"_bbp_old_topic_author_name_id":["Anonymous"],"_bbp_old_is_topic_anonymous_id":["false"],"_bbp_old_closed_status_id":["publish"],"_bbp_author_ip":[null],"_bbp_old_sticky_status_id":["normal"],"_bbp_likes_count":["0","0"],"_btv_view_count":["465"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["37251"],"_bbp_forum_id":["27791"],"_bbp_engagement":["158054","167277"],"_bbp_voice_count":["2"],"_bbp_reply_count":["1"],"_bbp_last_reply_id":["94442"],"_bbp_last_active_id":["94442"],"_bbp_last_active_time":["2019-09-17 17:18:22"]},"test":"fcnqp"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/37251","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\/37251\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=37251"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}