{"id":46642,"date":"2017-09-27T11:19:28","date_gmt":"2017-09-27T11:19:28","guid":{"rendered":"\/forum\/forums\/topic\/compute-the-derivative-of-an-arbitrary-varaible-in-a-fluent-udf\/"},"modified":"2017-09-27T11:19:28","modified_gmt":"2017-09-27T11:19:28","slug":"compute-the-derivative-of-an-arbitrary-varaible-in-a-fluent-udf","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/compute-the-derivative-of-an-arbitrary-varaible-in-a-fluent-udf\/","title":{"rendered":"Compute the derivative of an arbitrary varaible in a FLUENT UDF"},"content":{"rendered":"<p>User can set a dummy user defined scalar (do not need to solve that UDS), assign the varible he wants to compute the gradient to that UDS. Then use the following udf: #include &#8220;udf.h&#8221; DEFINE<em>EXECUTE<\/em>AT<em>END(my<\/em>adjust) { Domain *d=Get<em>Domain(1); Thread *t; cell<\/em>t c; thread<em>loop<\/em>c(t,d) { begin<em>c<\/em>loop(c,t) C<em>UDSI(c,t,0)=C<\/em>U(c,t); end<em>c<\/em>loop(c,t) } Alloc<em>Storage<\/em>Vars(d, SV<em>UDSI<\/em>RG(0), SV<em>UDSI<\/em>G(0), SV<em>NULL); Scalar<\/em>Reconstruction(d, SV<em>UDS<\/em>I(0), -1, SV<em>UDSI<\/em>RG(0), NULL); Scalar<em>Derivatives (d, SV<\/em>UDS<em>I(0), -1, SV<\/em>UDSI<em>G(0), SV<\/em>UDSI<em>RG(0), NULL); thread<\/em>loop<em>c(t,d) { begin<\/em>c<em>loop(c,t) { C<\/em>UDMI(c,t,0)=C<em>UDSI<\/em>G(c,t,0)[0]; C<em>UDMI(c,t,1)=C<\/em>UDSI<em>G(c,t,0)[1]; C<\/em>UDMI(c,t,2)=C<em>UDSI<\/em>G(c,t,0)[2]; } end<em>c<\/em>loop(c,t) } Free<em>Storage<\/em>Vars(d,SV<em>UDSI<\/em>RG(0), SV<em>UDSI<\/em>G(0), SV_NULL); }<\/p>\n","protected":false},"template":"","class_list":["post-46642","topic","type-topic","status-closed","hentry"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_old_topic_id":["18827"],"_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","0","0","0"],"_btv_view_count":["927"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["46642"],"_bbp_forum_id":["27792"],"_bbp_engagement":["154160"],"_bbp_voice_count":["1"],"_bbp_reply_count":["1"],"_bbp_last_reply_id":["122633"],"_bbp_last_active_id":["122633"],"_bbp_last_active_time":["2017-09-27 11:19:28"]},"test":"admin-2"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/46642","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\/46642\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=46642"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}