{"id":291007,"date":"2023-06-29T19:38:44","date_gmt":"2023-06-29T19:38:44","guid":{"rendered":"\/forum\/forums\/topic\/eulerian-ddpm-floating-point-exception-error-still-persists\/"},"modified":"2023-06-29T19:38:44","modified_gmt":"2023-06-29T19:38:44","slug":"eulerian-ddpm-floating-point-exception-error-still-persists","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/eulerian-ddpm-floating-point-exception-error-still-persists\/","title":{"rendered":"Eulerian DDPM | Floating Point Exception Error Still Persists"},"content":{"rendered":"<p><span style=\"font-size: 10pt\">(Appologies, thinking I had posted on wrong forum, I flagged my own question, so re-posting here)<\/span><\/p>\n<p><span style=\"font-size: 10pt\">Good day,<\/span><\/p>\n<p><span style=\"font-size: 10pt\">I am solving mixing of high volume fraction of particles in water (transient, Eulerian, DDPM, kwsst, Coupled, injection). The issue is that simulation solves and converges (as per both residuals and monitored variables) for the first <strong>flow<\/strong> timestep, but when the flow timestep is bumping to the second one, continuity and k, e residuals fly up to 10 orders of magnitude, and then there is this <em><strong>Experiencing convergence difficulties<\/strong>&nbsp;<\/em>warning before I get<strong><em> floating point exception<\/em><\/strong> and simulation is terminated. <\/span><\/p>\n<p><span style=\"font-size: 10pt\">My background effort to fix the issue has been the following, however, I have tried them one at a time for most of them to see individual effect each could have had, but unfortunately in vain:<\/span><\/p>\n<ul>\n<li><span style=\"font-size: 10pt\">Solving the flow to a stable state before injecting<\/span><\/li>\n<li><span style=\"font-size: 10pt\">refining the mesh ( Watertight\/ Polyhedral or Polyhedral Hex Core &#8211; <strong>Orth<\/strong>: min. 0.3 &#8211; avg 0.95&nbsp; |&nbsp; <strong>Skew<\/strong>: max 0.7 avg 0.04&nbsp; |&nbsp; <strong>AspR<\/strong>: Max 19.9 &#8211; avg 1.75), <\/span><\/li>\n<li><span style=\"font-size: 10pt\">solving for timesteps as small as 0.002 [s], <\/span><\/li>\n<li><span style=\"font-size: 10pt\">compromising on injections as small as parcel count of 2 (while keeping DDPM active), <\/span><\/li>\n<li><span style=\"font-size: 10pt\">manipulating URF&#8217;s of momentum, pressure, k and e for as low as 0.2 (pressure) and 0.5 for the rest, as the manulal says<\/span><\/li>\n<li><span style=\"font-size: 10pt\">increasing number of DPM updates per flow timestep and reducing DPM source URF to make sure DPM sources are fully consumed in each timestep.<\/span><\/li>\n<\/ul>\n<p><span style=\"font-size: 10pt\">Since tank top is open in reality, I define <strong>zero-shear wall <\/strong>and <strong>escape <\/strong>as boundary condition for top open surface and DPM, which I believe should not be a deal. I still have not fumbled with Flow Courant Number and the DPM tracking length scale.<\/span><\/p>\n<p><span style=\"font-size: 10pt\">But there is nothing else I can either find online or think of on my own.<\/span><\/p>\n<p><span style=\"font-size: 10pt\">Can anyone help please?<\/span><\/p>\n","protected":false},"template":"","class_list":["post-291007","topic","type-topic","status-closed","hentry","topic-tag-ddpm","topic-tag-dramine-1","topic-tag-mixing-tank","topic-tag-rob-2"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["130676","852"],"_bbp_author_ip":["23.206.193.146"]," _bbp_last_reply_id":["0"]," _bbp_likes_count":["0"],"_btv_view_count":["557"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["291007"],"_bbp_forum_id":["27796"],"_bbp_engagement":["852","130676"],"_bbp_voice_count":["2"],"_bbp_reply_count":["6"],"_bbp_last_reply_id":["291295"],"_bbp_last_active_id":["291295"],"_bbp_last_active_time":["2023-07-03 13:55:35"]},"test":"sardar-svngmail-com"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/291007","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\/291007\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=291007"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}