{"id":398561,"date":"2024-12-26T23:35:48","date_gmt":"2024-12-26T23:35:48","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/negative-initial-flow-rate-in-ansys-cfx-2-way-fsi\/"},"modified":"2024-12-26T23:35:48","modified_gmt":"2024-12-26T23:35:48","slug":"negative-initial-flow-rate-in-ansys-cfx-2-way-fsi","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/negative-initial-flow-rate-in-ansys-cfx-2-way-fsi\/","title":{"rendered":"Negative initial flow rate in Ansys CFX 2-way FSI"},"content":{"rendered":"<p>&lt;p&gt;Hi all,&lt;br&gt;&lt;br&gt;First, Merry Christmas and Happy New Year!&lt;br&gt;&lt;br&gt;I am recently trying to run a 2-way FSI with Ansys CFX and Transient Structural modules. It is a physiological case hence I set my initial pressure condition in CFX to 10666 Pa (80 mmHg equivalent). I verified the settings by running standalone CFX and Structural modules, respectively, and there is no problem.&lt;br&gt;&lt;br&gt;However, during my coupling, my&nbsp;<strong>initial flow rate output from CFX is negative<\/strong>. I had never seen this situation before from CFD, and ideally the first step should not produce a large displacement transfer back to the fluid domain.&lt;br&gt;&lt;br&gt;I am therefore wondering,&nbsp;<strong>how do CFX and Transient Structural initialise the solution at the first step.<\/strong>&lt;br&gt;&lt;br&gt;A few things I have tried:&lt;br&gt;- 1-way FSI from CFX to Transient Structural only: no problem&lt;br&gt;- 2-way FSI but change the material property to ** structural steel **: no problem, but not physiologically true.&lt;br&gt;- lower my initial pressure: my initial flow rate is less negative, but does not really make a diff.&lt;\/p&gt;<\/p>\n","protected":false},"template":"","class_list":["post-398561","topic","type-topic","status-publish","hentry","topic-tag-2-way-coupled-fsi","topic-tag-ansys-cfx","topic-tag-mass-flow-rate-1","topic-tag-system-coupling","topic-tag-transient-structural"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_forum_id":["27792"],"_bbp_topic_id":["398561"],"_bbp_subscription":["47694","805"],"_bbp_author_ip":["2a00:23cc:b74f:2701:b931:4e15:35e6:7b48"],"_bbp_last_reply_id":["407375"],"_bbp_last_active_id":["407375"],"_bbp_last_active_time":["2025-01-28 11:10:33"],"_bbp_reply_count":["1"],"_bbp_reply_count_hidden":["0"],"_bbp_voice_count":["2"],"_bbp_engagement":["47694","805"],"_btv_view_count":["242"],"_bbp_topic_status":["unanswered"]},"test":"6811154a69189dbf3dea8551d366ebac69e385c4"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/398561","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\/398561\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=398561"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}