{"id":286768,"date":"2023-06-01T17:37:31","date_gmt":"2023-06-01T17:37:31","guid":{"rendered":"\/forum\/forums\/topic\/problem-in-solving-transport-equation-using-uds-2\/"},"modified":"2023-06-02T12:42:10","modified_gmt":"2023-06-02T12:42:10","slug":"problem-in-solving-transport-equation-using-uds-2","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/problem-in-solving-transport-equation-using-uds-2\/","title":{"rendered":"problem in solving transport equation using UDS"},"content":{"rendered":"<p>Hello everyone,&nbsp;<\/p>\n<p>I am trying to compute the platelet lysis index (PLI) in my simulations by solving this transport equation:&nbsp;<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/06\/01-06-2023-1685639936-mceclip0.png\" width=\"630\" height=\"83\"><\/p>\n<p>where tau is the shear stress.&nbsp;<\/p>\n<p>My simulations are steady state, so if I have understood correctly from Ansys Fluent User Guide, this is the type of equation I am solving in Fluent with the diffusion coefficient equal to zero:<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/06\/01-06-2023-1685640211-mceclip1.png\" width=\"662\" height=\"87\"><\/p>\n<p>I have prepared the UDF for my source term:<\/p>\n<p><img decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/06\/01-06-2023-1685640269-mceclip2.png\"><\/p>\n<p>To obtain convergence in my simulations I had to change the under relaxation factor of my UDS to 0.50.<\/p>\n<p>After runnign my simulation I use CFD post to compute the power of my scalar (PLI = scalar 0 ^(1\/0.77)).<\/p>\n<p>I am expecting a PLI distribution similar to this:<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/06\/01-06-2023-1685640599-mceclip4.png\" width=\"523\" height=\"459\"><\/p>\n<p>But the resuls that I get are like this:<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/06\/01-06-2023-1685640639-mceclip5.png\" width=\"867\" height=\"483\"><\/p>\n<p>&nbsp;<\/p>\n<p>I also tried on a simplier geometry and I think that the results are stil wrong in terms of values but the colormap is more similar to what I am supposed to obtain:<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/06\/01-06-2023-1685640564-mceclip3.png\" width=\"665\" height=\"435\"><\/p>\n<p>I was wondering if there is something wrong in my code for the source term or if this might be related to something else?<\/p>\n<p>Thank you in advance!<\/p>\n<p>Claudia<\/p>\n","protected":false},"template":"","class_list":["post-286768","topic","type-topic","status-closed","hentry","topic-tag-convergence-1","topic-tag-fluent-1","topic-tag-blood-flow","topic-tag-fluent-uds","topic-tag-uds","topic-tag-under-relaxation-factor-1"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["261033"],"_bbp_author_ip":["23.217.200.46"]," _bbp_last_reply_id":["0"]," _bbp_likes_count":["0"],"_btv_view_count":["260"],"_edit_lock":["1685641181:188377"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["286768"],"_bbp_forum_id":["27792"],"_bbp_engagement":["261033"],"_bbp_voice_count":["1"],"_bbp_reply_count":["0"],"_bbp_last_reply_id":["0"],"_bbp_last_active_id":["286768"],"_bbp_last_active_time":["2023-06-01 17:37:31"]},"test":"3831efb3fcdd393755e6579984b42ad9059c6826"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/286768","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\/286768\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=286768"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}