{"id":368255,"date":"2024-05-23T08:22:24","date_gmt":"2024-05-23T08:22:24","guid":{"rendered":"\/forum\/forums\/topic\/low-drag-coefficient-for-sphere\/"},"modified":"2024-05-23T08:22:24","modified_gmt":"2024-05-23T08:22:24","slug":"low-drag-coefficient-for-sphere","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/low-drag-coefficient-for-sphere\/","title":{"rendered":"Low drag coefficient for sphere"},"content":{"rendered":"<p>I am conducting a simulation of a smooth sphere traveling through a flow to compare with experimental results. However, the drag coefficient obtained from the simulation is significantly lower (Cd = 0.11426044) compared to the experimental Cd of 0.45. The reference value settings are correctly adjusted, making it less likely the cause of the issue. I tried refining the mesh by decreasing the face and body sizing of the sphere and domain, but the Cd value still does not match the experimental results. I also adjusted the wall y+ value using the inflation of 10 layers with the first layer cell height obtained from the wall y+ calculator, which gave me a first layer height of 0.000738208399739557 m corresponding to wall y+ = 50. I need a wall y+ value between 30 and 200 as I am using the realizable k-epsilon model. However, when I calculate the wall y+ of the sphere in Fluent, it only shows 19. Can anyone tell me what I am doing wrong? link to Y+ calculator:&nbsp;<a class=\"relative pointer-events-auto a\n  \n  \n  \n  \n  hover:underline\n  \" href=\"https:\/\/volupe.se\/wall-y-calculator-when-meshing-a-geometry-for-cfd-analysis-this-handy-volupe-calculator-computes-the-height-of-the-first-mesh-cell-off-the-wall-required-to-achieve-a-desired-y-using-flat-plate-boun\/\" target=\"_blank\" rel=\"noopener nofollow ugc\">https:\/\/volupe.se\/wall-y-calculator-when-meshing-a-geometry-for-cfd-analysis-this-handy-volupe-calculator-computes-the-height-of-the-first-mesh-cell-off-the-wall-required-to-achieve-a-desired-y-using-flat-plate-boun\/<\/a><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2024\/05\/23-05-2024-1716452441-Screenshot 2024-05-23 155720.png\" alt=\"\" width=\"1470\" height=\"791\"><img loading=\"lazy\" decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2024\/05\/23-05-2024-1716452343-Screenshot 2024-05-23 155123.png\" alt=\"\" width=\"1265\" height=\"679\"><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2024\/05\/23-05-2024-1716452492-Screenshot 2024-05-23 155227.png\" alt=\"\" width=\"1582\" height=\"849\"><\/p>\n","protected":false},"template":"","class_list":["post-368255","topic","type-topic","status-closed","hentry","topic-tag-ansys-cfd-1","topic-tag-drag-coefficient","topic-tag-fluent","topic-tag-sphere"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["349517","8124","117676"],"_bbp_author_ip":["184.24.96.177"]," _bbp_last_reply_id":["0"]," _bbp_likes_count":["0"],"_btv_view_count":["872"],"_bbp_topic_status":["unanswered"],"_bbp_topic_id":["368255"],"_bbp_forum_id":["27792"],"_bbp_engagement":["8124","117676","349517"],"_bbp_voice_count":["3"],"_bbp_reply_count":["8"],"_bbp_last_reply_id":["369192"],"_bbp_last_active_id":["369192"],"_bbp_last_active_time":["2024-05-30 09:04:54"]},"test":"zaize4355gmail-com"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/368255","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\/368255\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=368255"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}