{"id":282310,"date":"2023-05-04T09:32:03","date_gmt":"2023-05-04T09:32:03","guid":{"rendered":"\/forum\/forums\/topic\/transient-mass-transfer-rate-and-under-relaxation-factors\/"},"modified":"2023-05-04T09:32:03","modified_gmt":"2023-05-04T09:32:03","slug":"transient-mass-transfer-rate-and-under-relaxation-factors","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/transient-mass-transfer-rate-and-under-relaxation-factors\/","title":{"rendered":"Transient mass transfer rate and under relaxation factors"},"content":{"rendered":"<p>Hello,<\/p>\n<p>I am simulating the mass transfer of O2 from air to water in an Eulerian multiphase bioreactor system. To calculate the mass transfer coefficient I need the concentration profile of o2 that is transferred from air to water over time and I would simulate that on a frozen air-water system.&nbsp;<br \/>The problem I am dealing with is that the convergence of the system is dependent on lowering the under-relaxation factor (especially when the simulation is close to saturation concentration of oxygen ) and at the same time the calculated concentration at each time step heavily depends on the URF (and at the end the concentration profile affects the calculated kla value ).<\/p>\n<p>Should I change the no of iterations so that it reduces the URF effect?<\/p>\n<p>What is the right approach here, should I just choose the URF that fits the profile with experimental data?&nbsp;<\/p>\n<p>Thanks,<\/p>\n","protected":false},"template":"","class_list":["post-282310","topic","type-topic","status-closed","hentry","topic-tag-Interphasemasstransfer-1","topic-tag-mass-transfer","topic-tag-multiphase-eulerian","topic-tag-under-relaxation-factors"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["231872","199"],"_bbp_author_ip":["23.220.96.180"]," _bbp_last_reply_id":["0"]," _bbp_likes_count":["0"],"_btv_view_count":["844"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["282310"],"_bbp_forum_id":["27792"],"_bbp_engagement":["199","231872"],"_bbp_voice_count":["2"],"_bbp_reply_count":["15"],"_bbp_last_reply_id":["282963"],"_bbp_last_active_id":["282963"],"_bbp_last_active_time":["2023-05-09 08:30:56"]},"test":"majamkt-dtu-dk"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/282310","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\/282310\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=282310"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}