{"id":294015,"date":"2023-07-20T06:51:04","date_gmt":"2023-07-20T06:51:04","guid":{"rendered":"\/forum\/forums\/topic\/continuity-residual-stays-flat-but-not-converging-down-to-1e-3-or-lower\/"},"modified":"2023-07-20T06:58:08","modified_gmt":"2023-07-20T06:58:08","slug":"continuity-residual-stays-flat-but-not-converging-down-to-1e-3-or-lower","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/continuity-residual-stays-flat-but-not-converging-down-to-1e-3-or-lower\/","title":{"rendered":"Continuity residual stays flat but not converging down to 1E-3 or lower"},"content":{"rendered":"

I am conducting a drag analysis on a Ahmed Body.
I learnt that in general, one should not merely rely on convergence plot in the residual graph to conclude the accuracy of the simulation, some desired parameters need to be monitored as well.<\/p>\n

Here is my current result on residual and cd (desired parameter monitored):<\/p>\n

<\/a><\/p>\n

<\/a><\/p>\n

I would like to ask:
1. Is it numerically reasonable for some types of simulations, allowing residuals of some parameters (e.g. k, continuity, veloctiy components) not truly converging but staying flat consistently at 1E-1\/1E-2. How can I determine (in what types of simulation) if further improvement or refinement need or I should tolerate and allow the flat residual and focus on the desired parameter monitoring? How to judge overall?<\/p>\n

2. Regarding the y+ value capturing boundary layer fluid viscous behavior, I heard that y+ value should be <1 for the viscous sublayer, some says 30 < y+ < 300 (correct me if I mess sth up plz). By some calculations in my case on ahmed body, y (first layer height) is so small (like 1e-5 meter) and aspect ratio will be high which causing poor mesh quality near inflation layers. How can I generally define a proper layers for capture turbulence while maintaining good mesh quality? <\/p>\n

Thank you for answering and addressing my struggles!!<\/p>\n","protected":false},"template":"","class_list":["post-294015","topic","type-topic","status-closed","hentry","topic-tag-Ahmedbody-1","topic-tag-drag-coefficient"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["187526","730"],"_bbp_author_ip":["23.33.28.204"]," _bbp_last_reply_id":["0"]," _bbp_likes_count":["0"],"_btv_view_count":["6510"],"_edit_lock":["1689836034:72927"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["294015"],"_bbp_forum_id":["27792"],"_bbp_engagement":["730","187526"],"_bbp_voice_count":["2"],"_bbp_reply_count":["1"],"_bbp_last_reply_id":["294264"],"_bbp_last_active_id":["294264"],"_bbp_last_active_time":["2023-07-21 10:44:17"]},"test":"jasonsum"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/294015","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\/294015\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=294015"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}