{"id":373075,"date":"2024-07-22T16:55:09","date_gmt":"2024-07-22T16:55:09","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/373075\/"},"modified":"2024-07-22T16:55:09","modified_gmt":"2024-07-22T16:55:09","slug":"373075","status":"publish","type":"reply","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/373075\/","title":{"rendered":"Reply To: ANSYS fluent \u2013 Rocky DEM coupling"},"content":{"rendered":"<p>&lt;p&gt;Dear Rob and Vinicius,&lt;\/p&gt;&lt;p&gt;Thank you for your suggustions.&nbsp;&lt;\/p&gt;&lt;p&gt;1- about the semi-resolved so basically i can not use semi-resolved if i want to measure the drag force and it can just be used for particles distribution . Correct ?&lt;\/p&gt;&lt;p&gt;I have done simulation with 24R1 too with a fine mesh and 0.001s time step and same issue comes up that simulation does not proceed.&nbsp;&lt;\/p&gt;&lt;p&gt;2- Before Rob mentioned that he suggusts that instead of using a tetra\/hexa combination just use tetra with lower time step. I ran a simulation with 0.001 and 0.0005 time steps and 4.67e-6 DEM time step&nbsp; with the attached mesh. the one with 0.001s crashed and gave the follwing error and simulation stopped before even 0.1s of simulation output :&nbsp;&lt;\/p&gt;&lt;p&gt;DEM-CFD critical explicit time step:&lt;br&gt;6.19% of the particles exceeded 50% the CFD critical explicit time step.&lt;br&gt;3.23% of the particles exceeded 75% the CFD critical explicit time step.&lt;br&gt;&lt;br&gt;&lt;\/p&gt;&lt;p&gt;The one with 0.0005s time step , went to 9s and gave the following error and particles agglomorated (picture attached )but the simulation were still running:&nbsp;&lt;\/p&gt;&lt;p&gt;DEM-CFD critical explicit time step:&lt;br&gt;0.183% of the particles exceeded 50% the CFD critical explicit time step.&lt;br&gt;0.0913% of the particles exceeded 75% the CFD critical explicit time step.&lt;br&gt;0.0913% of the particles exceeded 100% the CFD critical explicit time step. collected in 11 events of CFD forces.&nbsp;&lt;\/p&gt;&lt;p&gt;I want to know why it took the simulation 9s to give the error and suddenly got unstable , if there is a problem why it did not gave the error begining of the simulation ?&lt;\/p&gt;&lt;p&gt;&nbsp;&lt;\/p&gt;&lt;p&gt;3- i ran one or two with SPH and particles agglomorated , i will try again SPH and with lower time step of DEM and let you know.&lt;\/p&gt;&lt;p&gt;Thanks&nbsp;&lt;\/p&gt;&lt;p&gt;<img decoding=\"async\" src=\"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2024\/07\/22-07-2024-1721666595-mceclip0.png\" \/>&lt;\/p&gt;&lt;p&gt;<img decoding=\"async\" src=\"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2024\/07\/22-07-2024-1721667264-mceclip1.png\" \/>&lt;\/p&gt;&lt;p&gt;&nbsp;&lt;\/p&gt;<\/p>\n","protected":false},"template":"","class_list":["post-373075","reply","type-reply","status-publish","hentry"],"aioseo_notices":[],"acf":[],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/replies\/373075","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/replies"}],"about":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/types\/reply"}],"version-history":[{"count":0,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/replies\/373075\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=373075"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}