{"id":167450,"date":"2022-03-18T01:55:54","date_gmt":"2022-03-18T01:55:54","guid":{"rendered":"\/forum\/forums\/topic\/fluent-time-step-too-small\/"},"modified":"2022-03-18T14:33:35","modified_gmt":"2022-03-18T14:33:35","slug":"fluent-time-step-too-small","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/fluent-time-step-too-small\/","title":{"rendered":"[FLUENT] Time step too small"},"content":{"rendered":"<div class=\"Item-Body\">\n<div class=\"Message userContent\">\n<p>I am running a transient, incompressible, turbulent (SST k-w), single-phase simulation with the pressure-based solver (coupled solver). I have several different length scales in the problem so I have widely varying mesh densities across the geometry in order to resolve the boundary layer and flow features everywhere. My timestep is dropping to 1e-8 s using the Adaptive Method even with Courant number up to 20. This is unreasonably low. Am I just out of luck with this simulation at my current mesh density?<\/p>\n<p>One thing I note is that for the steady-state solve the residuals take quite a while to drop but when moving to transient solve they drop quickly and converge quickly (albeit with dt = 1e-8). What can this be indicative of?<\/p>\n","protected":false},"template":"","class_list":["post-167450","topic","type-topic","status-closed","hentry"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_btv_view_count":["2512"],"_bbp_likes_count":["0"],"_bbp_subscription":["245829"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["167450"],"_bbp_forum_id":["27792"],"_bbp_engagement":["199","22555","191131","245829"],"_bbp_voice_count":["4"],"_bbp_reply_count":["5"],"_bbp_last_reply_id":["208761"],"_bbp_last_active_id":["208761"],"_bbp_last_active_time":["2022-03-18 14:33:35"]},"test":"lcosta1984gmail-com"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/167450","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\/167450\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=167450"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}