{"id":29839,"date":"2018-07-30T01:27:29","date_gmt":"2018-07-30T01:27:29","guid":{"rendered":"\/forum\/forums\/topic\/wall-skin-friction\/"},"modified":"2018-07-30T01:27:29","modified_gmt":"2018-07-30T01:27:29","slug":"wall-skin-friction","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/wall-skin-friction\/","title":{"rendered":"Wall Skin Friction"},"content":{"rendered":"<p>I am trying to model turbulent flow in a pipe.&nbsp; I am looking at the wall skin friction and comparing it to the Blasius equation.&nbsp; I am using a 2d-axisymmetric model that is 0.01905 m by 5 m long and a structured bias mesh that is smaller close to the wall.&nbsp; The y+ values are in the range of 0.6 &#8211; 0.65.&nbsp; Using a k-e model with enhanced wall treatments with a inlet velocity of 0.1 m\/s (3791 Reynolds number) the wall skin friction is 0.0120925 vs 0.010068 from the Blasius equation, a result that is about 28% high.&nbsp; When the velocity is changed to 0.2 m\/s (7583 Reynolds number) the will skin friction becomes 0.0373416 vs 0.008466 from the Blasius equation, a result that is about 341% high.&nbsp;&nbsp;<\/p>\n<p><\/p>\n<p>So my question is why does the turbulence model not scale as the Reynolds number increases?&nbsp; Is it the mesh?&nbsp; I have tried a finer mesh with the same results.&nbsp; Is it something with the turbulence model?&nbsp; I have tried the transition SST model but the results are flipped, the 0.2 m\/s is around 20% off and the 0.1 m\/s is around 300% off.&nbsp; Is there not a way to scale the model?<\/p>\n<p><\/p>\n<p>I was hoping to be able to match a friction factor to the flow that would be applied at several different flow rates to verify the model before moving on to some other tasks.&nbsp;<\/p>\n","protected":false},"template":"","class_list":["post-29839","topic","type-topic","status-closed","hentry"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_old_topic_id":["2008"],"_bbp_old_topic_author_name_id":["Anonymous"],"_bbp_old_is_topic_anonymous_id":["false"],"_bbp_old_closed_status_id":["publish"],"_bbp_author_ip":[null],"_bbp_old_sticky_status_id":["normal"],"_bbp_likes_count":["0","0","0","0","0"],"_btv_view_count":["987"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["29839"],"_bbp_forum_id":["27792"],"_bbp_engagement":["22555","157143","182541"],"_bbp_voice_count":["3"],"_bbp_reply_count":["2"],"_bbp_last_reply_id":["130987"],"_bbp_last_active_id":["130987"],"_bbp_last_active_time":["2020-10-23 20:40:12"]},"test":"terjit"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/29839","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\/29839\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=29839"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}