{"id":218336,"date":"2022-07-12T21:06:14","date_gmt":"2022-07-12T21:06:14","guid":{"rendered":"\/forum\/forums\/topic\/turbulent-viscosity-limit\/"},"modified":"2022-07-12T21:07:42","modified_gmt":"2022-07-12T21:07:42","slug":"turbulent-viscosity-limit","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/turbulent-viscosity-limit\/","title":{"rendered":"Turbulent Viscosity Limit"},"content":{"rendered":"<p class=\"MsoNormal\" style=\"line-height: normal\"><span style=\"font-size: 12.0pt;font-family: 'Times New Roman',serif\">Hi all, I have been encountering this problem shown in the pic with simulations with parameters:<\/span><\/p>\n<ul type=\"disc\">\n<li class=\"MsoNormal\" style=\"line-height: normal\"><span style=\"font-size: 12.0pt;font-family: 'Times New Roman',serif\">RNG k-epsilon Transient<\/span><\/li>\n<li class=\"MsoNormal\" style=\"line-height: normal\"><span style=\"font-size: 12.0pt;font-family: 'Times New Roman',serif\">Pressure-based Coupled scheme<\/span><\/li>\n<li class=\"MsoNormal\" style=\"line-height: normal\"><span style=\"font-size: 12.0pt;font-family: 'Times New Roman',serif\">massflow inlet and pressure outlet BC with Intensity 5% and Hydraulic Diameter 0.012m for Turbulence Specification Method<\/span><\/li>\n<li class=\"MsoNormal\" style=\"line-height: normal\"><span style=\"font-size: 12.0pt;font-family: 'Times New Roman',serif\">URF and Courant number 0.2 while Turbulent Viscosity 1<\/span><\/li>\n<ul type=\"circle\">\n<li class=\"MsoNormal\" style=\"line-height: normal\"><strong><span style=\"font-size: 12.0pt;font-family: 'Times New Roman',serif\">Three boxes for Frozen Flux Formulation, Warped-face Gradient Correction, Higher order term relaxation<\/span><\/strong><\/li>\n<\/ul>\n<li class=\"MsoNormal\" style=\"line-height: normal\"><span style=\"font-size: 12.0pt;font-family: 'Times New Roman',serif\">Timestep size 0.002 and 25 iteration\/timestep<\/span><\/li>\n<\/ul>\n<p class=\"MsoNormal\" style=\"line-height: normal\"><span style=\"font-size: 12.0pt;font-family: 'Times New Roman',serif\">The problem occurs when the three boxes are checked, the number of cell overlimit starts very low and gradually builds up to such level after around 20 timesteps. When the three boxes are unchecked, overlimit cells range between 1 and 9 and disappear soon after.<\/span><\/p>\n<p class=\"MsoNormal\" style=\"line-height: normal\"><span style=\"font-size: 12.0pt;font-family: 'Times New Roman',serif\">Online posts suggested me to drop timestep size, max iteration per timestep, and URF but they don&#8217;t seem to work for me. Especially when URF are quite low already. Assuming I wish to keep those 3 boxes checked, does anyone has any ideas? I have been bugged for long. The model is also attached. Thanks a lot!<\/span><\/p>\n<p class=\"MsoNormal\" style=\"line-height: normal\"><span style=\"font-size: 12.0pt;font-family: 'Times New Roman',serif\"><img decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2022\/07\/12-07-2022-1657660035-mceclip1.png\"><img decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2022\/07\/12-07-2022-1657660027-mceclip0.png\"><\/span><\/p>\n","protected":false},"template":"","class_list":["post-218336","topic","type-topic","status-closed","hentry","topic-tag-turbulence","topic-tag-turbulence-intensity","topic-tag-turbulence-model","topic-tag-turbulent","topic-tag-turbulent-flow","topic-tag-turbulent-model","topic-tag-viscosity"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["240427","25","22555","199"],"_bbp_author_ip":["23.218.93.111"]," _bbp_last_reply_id":["0"]," _bbp_likes_count":["0"],"_btv_view_count":["2160"],"_edit_lock":["1657660011:165435"],"_bbp_likes_count":["0"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["218336"],"_bbp_forum_id":["27792"],"_bbp_engagement":["25","199","22555","240427"],"_bbp_voice_count":["4"],"_bbp_reply_count":["8"],"_bbp_last_reply_id":["218803"],"_bbp_last_active_id":["218803"],"_bbp_last_active_time":["2022-07-18 18:43:58"]},"test":"ianyylaicsu-fullerton-edu"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/218336","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\/218336\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=218336"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}