{"id":377282,"date":"2024-08-05T16:48:47","date_gmt":"2024-08-05T16:48:47","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/rocky-fluent-coupling\/"},"modified":"2024-08-06T13:41:52","modified_gmt":"2024-08-06T13:41:52","slug":"rocky-fluent-coupling","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/rocky-fluent-coupling\/","title":{"rendered":"Rocky- fluent coupling"},"content":{"rendered":"<p>Hello,<\/p>\n<p>I am doing a CFD-DEM coupling of a mixing tank and I have a question.<\/p>\n<p>at first the simulation is running ok for a few seconds then particles start to agglomorrate (image attached from before and after) and I recieve the following messages from fluent and Rocky:&nbsp;<\/p>\n<p>Rocky : solid maximum volume fraction 0.65% did not achieve after 500 iterations&nbsp;<\/p>\n<p>Fluent: turbulent viscosity limited to viscosity ratio of 1.000000+05 in 29436 cells.<\/p>\n<p>the number of cells will increase over time and then I get the following error and particle disappear :&nbsp;<\/p>\n<p>DEM-CFD critical explicit time step:<br \/>0.183% of the particles exceeded 50% the CFD critical explicit time step.<br \/>0.0913% of the particles exceeded 75% the CFD critical explicit time step.<br \/>0.0913% of the particles exceeded 100% the CFD critical explicit time step. collected in 11 events of CFD forces.<\/p>\n<p>my particle size is bigger than the mesh size and i thought since Rocky uses iteration for volumetric diffusion there is no issue with it. I want to know if that is the problem which is causing the issue or it is because another reason ?<\/p>\n<p>I have run the simulation with the following time steps and same issue came up.&nbsp;<\/p>\n<p>CFD: 5e-4s DEM: 4.67e-6 , 5e-7 , 1e-8s&nbsp;<\/p>\n<p>CFD: 5E-5S DEM: 4.67e-6 , 5e-7<\/p>\n<p>Thanks&nbsp;<\/p>\n<p><img decoding=\"async\" src=\"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2024\/08\/05-08-2024-1722876129-mceclip1.png\"><\/p>\n<p><img decoding=\"async\" src=\"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2024\/08\/05-08-2024-1722876102-mceclip0.png\"><\/p>\n","protected":false},"template":"","class_list":["post-377282","topic","type-topic","status-closed","hentry"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["57165","66199"],"_bbp_author_ip":["137.99.69.128"]," _bbp_last_reply_id":["0"]," _bbp_likes_count":["0"],"_btv_view_count":["778"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["377282"],"_bbp_forum_id":["27792"],"_bbp_engagement":["57165","66199"],"_bbp_voice_count":["2"],"_bbp_reply_count":["3"],"_bbp_last_reply_id":["377399"],"_bbp_last_active_id":["377399"],"_bbp_last_active_time":["2024-08-06 13:40:21"]},"test":"98fda2c5151906a025703ec623e093a5a38a4681"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/377282","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\/377282\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=377282"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}