{"id":41447,"date":"2020-03-03T17:46:16","date_gmt":"2020-03-03T17:46:16","guid":{"rendered":"\/forum\/forums\/topic\/induced-drag-calculation-with-udf-or-expression\/"},"modified":"2020-03-03T17:46:16","modified_gmt":"2020-03-03T17:46:16","slug":"induced-drag-calculation-with-udf-or-expression","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/induced-drag-calculation-with-udf-or-expression\/","title":{"rendered":"Induced Drag Calculation with UDF or Expression"},"content":{"rendered":"<p>Hallo Everyone,<\/p>\n<p><\/p>\n<p>I need your expertise with dire urge. I am planning to calculate the Induced Drag component of&nbsp; 3D Wing using the Far-Field Technique (also known as Trefftz Plane method)<\/p>\n<p><\/p>\n<p>For that i neeed to run a surface integral of the momentum equation on a 2D plane which is perpendicular to the flow velocity U.<\/p>\n<p><\/p>\n<p>The Model Diagram and the equation is as follows:<\/p>\n<p><\/p>\n<p><img decoding=\"async\" src=\"https:\/\/us.v-cdn.net\/6032193\/uploads\/attachments\/405947db-a5ac-4033-8eb7-ab4000fab322\/eebba214-c5de-46ae-b617-ab730120a655_12.jpg?width=690&amp;upscale=false\" alt=\"\"><img decoding=\"async\" src=\"https:\/\/us.v-cdn.net\/6032193\/uploads\/attachments\/405947db-a5ac-4033-8eb7-ab4000fab322\/20380ace-6539-4604-9ab7-ab730120dfa4_23.jpg?width=690&amp;upscale=false\" alt=\"\">al<\/p>\n<p><\/p>\n<p>As the equation says, i would like to access the Surface integral experssion. From there i would to access pertubation velocity components and multiply them with the area of the cell (dy * dz).<\/p>\n<p><\/p>\n<p>&nbsp;<\/p>\n<p><\/p>\n<p>Has anyone done this kind of calculation before? If anyone can provide any hints of doing thsi , it would be much appriciated.<\/p>\n<p><\/p>\n<p>&nbsp;<\/p>\n<p><\/p>\n<p>I have tried the UDF but I cant understand it very well and how to access the surface integral is still a challange for me.<\/p>\n<p><\/p>\n<p>Now I am looking at the Expression functionality in the post processor. Maybe that could allow me to key in my functions.<\/p>\n<p><\/p>\n<p>&nbsp;<\/p>\n<p><\/p>\n<p>Thanks for your kind support.<\/p>\n<p><\/p>\n<p>&nbsp;<\/p>\n<p><\/p>\n<p>Mohan Pannirselvam<\/p>\n<p><\/p>\n<p>Hamburg,Germany&nbsp;<\/p>\n","protected":false},"template":"","class_list":["post-41447","topic","type-topic","status-closed","hentry"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_old_topic_id":["13627"],"_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"],"_btv_view_count":["671"],"_bbp_subscription":["246460"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["41447"],"_bbp_forum_id":["27792"],"_bbp_engagement":["199","172160"],"_bbp_voice_count":["2"],"_bbp_reply_count":["1"],"_bbp_last_reply_id":["106907"],"_bbp_last_active_id":["106907"],"_bbp_last_active_time":["2020-03-04 12:00:58"]},"test":"mohanpannirselvam08"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/41447","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\/41447\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=41447"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}