{"id":311449,"date":"2023-10-13T16:30:17","date_gmt":"2023-10-13T16:30:17","guid":{"rendered":"\/forum\/forums\/topic\/drag-analysis-of-a-boat\/"},"modified":"2023-10-13T16:30:17","modified_gmt":"2023-10-13T16:30:17","slug":"drag-analysis-of-a-boat","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/drag-analysis-of-a-boat\/","title":{"rendered":"Drag analysis of a boat"},"content":{"rendered":"<p>I&rsquo;m currently simulating an enclosed boat in water.<br \/>I want to find the drag coefficient of the boat. I&rsquo;m currently achieving values of 0.09 for the drag coefficient which seems unrealistic.<br \/>I have attached the drag coefficient and lift coefficient plots below over a specific time frame.<\/p>\n<p>It would be preferred to have the boat moving up and down and implement waves at some point, however currently the drag coefficient is all I need. Which is why I feel this setup is good enough for the low speeds. Correct me if i&#8217;m wrong.<\/p>\n<p>I&rsquo;m currently using the following settings:<\/p>\n<p>Mesh-&gt; Around 3 million elements containing-<br \/>BOI at the back of the boat,<br \/>BOI around the boat and a long BOI at the waterline to refine mesh in these sections<br \/>General: Gravity , transient flow, pressure based solver, VOF open channel flow<br \/>Multiphase flow<br \/>K-Omega SST turbulence model<br \/>BC:<br \/>Pressure inlet and outlet<br \/>Open channel BC&rsquo;s<br \/>Velocity 1.5m\/s<br \/>Walls stationary<br \/>Waterline at 0.25m<\/p>\n<p>Solution settings:<br \/>PISO scheme<br \/>Gradient = Green- gauss cell based<br \/>Pressure = PRESTO<br \/>Remaining sections have Second order upwind<br \/>2500 time steps, time step size is 0.003<br \/>Transient formulation<span style=\"font-size: 14pt\">= First order implicit<\/span><\/p>\n<p>Can someone help me identify why I get such low drag coefficients or help me understand what I can do to ensure a reliable simulation for the drag forces. I would really appreciate a quick video call if possible.<img loading=\"lazy\" decoding=\"async\" style=\"font-size: 14pt\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/10\/13-10-2023-1697214506-mceclip1.png\" width=\"360\" height=\"219\"><img loading=\"lazy\" decoding=\"async\" style=\"font-size: 14pt\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/10\/13-10-2023-1697214493-mceclip0.png\" width=\"379\" height=\"219\"><img loading=\"lazy\" decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/10\/13-10-2023-1697214549-mceclip2.png\" width=\"435\" height=\"180\"><\/p>\n","protected":false},"template":"","class_list":["post-311449","topic","type-topic","status-closed","hentry","topic-tag-drag","topic-tag-drag-coefficient","topic-tag-fluent","topic-tag-hydrodynamic","topic-tag-multiphase","topic-tag-transient","topic-tag-waves"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["286419","5978"],"_bbp_author_ip":["168.143.243.24"]," _bbp_last_reply_id":["0"]," _bbp_likes_count":["0"],"_btv_view_count":["1370"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["311449"],"_bbp_forum_id":["27792"],"_bbp_engagement":["5978","286419"],"_bbp_voice_count":["2"],"_bbp_reply_count":["2"],"_bbp_last_reply_id":["320724"],"_bbp_last_active_id":["320724"],"_bbp_last_active_time":["2023-12-04 11:55:44"]},"test":"rjoosten741hotmail-com"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/311449","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\/311449\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=311449"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}